WO2015170588A1

WO2015170588A1 - Fuel injection valve

Info

Publication number: WO2015170588A1
Application number: PCT/JP2015/062166
Authority: WO
Inventors: 石井　英二; 正典石川; 一樹吉村; 秀治江原; 清隆小倉; 威生三宅
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2014-05-08
Filing date: 2015-04-22
Publication date: 2015-11-12
Also published as: JP2015214892A; JP6266428B2

Abstract

The present invention addresses the problem of preventing fuel remaining near the outlet of an injection nozzle from carbonizing, adhering as deposits, and changing the shape of spray and the flow rate of injection. This fuel injection valve is provided with: a circular conical seat surface coming into contact with a valve body and sealing fuel; and fuel injection nozzles having fuel injection hole inlet openings formed in the circular conical seat surface, the injection nozzles being configured so that injection hole axes which each connect the centers of the inlet and outlet of each of the fuel injection holes are configured to extend along different circular conical surfaces. The injection valve is characterized in that: the injection nozzles each have formed on the outlet side thereof a counterbore which does not function as an injection nozzle (that is, which does not function to control both the shape of spray and flow rate); the diameter of the opening of the counterbore is formed so as to increase toward the downstream side; and a stepped section is formed between the injection nozzle and the counterbore.

Description

Fuel injection valve

The present invention relates to a fuel injection valve used in an internal combustion engine such as a gasoline engine, in which fuel leakage is prevented by contacting the valve seat, and fuel injection is performed by separating the valve from the valve seat. Regarding the valve.

For example, Patent Document 1 is a background art in this technical field. In this publication, the surface roughness in the vicinity of the outlet side of the fuel injection hole is formed to be rough, and the sectional area of the outlet side of the fuel injection hole is formed to be larger than the sectional area of the inlet side. Deposits are volumed to prevent deposits from adhering to the fuel inlet side (metering section).

Another background art is, for example, Patent Document 2. In this publication, an oil repellent coating is continuously coated from the front end surface to the outer peripheral surface of the fuel injection hole, and the injection hole in the front end region of the fuel injection hole is formed in a stepped shape so that the injection hole near the valve seat By increasing the diameter of the nozzle hole at the tip, the fuel spray flow is prevented from adhering to the inner wall of the nozzle hole in the nozzle hole tip region, thereby preventing the occurrence of deposits.

JP 2007-315992 A JP 2007-32421 A

In a fuel injection device for an automobile engine, there is a problem that fuel remaining in the vicinity of the injection nozzle outlet is carbonized and deposited as a deposit during or after fuel injection. This deposit grows to the extent that it closes a part of the outlet of the injection nozzle with the use time of the injection device, and causes changes in the spray shape and the injection flow rate. Therefore, it is necessary to reduce the fuel remaining in the vicinity of the injection nozzle outlet during or after fuel injection.

In the above-mentioned Patent Document 1, the surface roughness in the vicinity of the outlet side of the fuel injection hole is formed to be rough, and the sectional area of the outlet side of the fuel injection hole is made larger than the sectional area of the inlet side. The deposit is made to be volumetric to prevent deposits from adhering to the fuel inlet side (metering section). However, this technique has a problem in that the deposit grows so as to block the injection nozzle outlet due to the structure in which the deposit is attached to the injection nozzle outlet, and as a result, the spray shape and the injection flow rate change over time.

Further, in Patent Document 2, an oil repellent coating is continuously coated from the front end surface to the outer peripheral surface of the fuel injection hole, and the injection hole in the front end region of the fuel injection hole is formed in a stepped shape so that the injection hole near the valve seat By increasing the diameter of the nozzle hole at the tip, the fuel spray flow is prevented from adhering to the inner wall of the nozzle hole in the nozzle hole tip region, thereby preventing the occurrence of deposits. However, in this technique, the fuel scattered from the spray remains in the stepped shape portion provided in the tip region of the fuel nozzle hole due to the surface tension effect of the step corner portion. Therefore, as a result, deposits are generated in the stepped shape portion, which causes a problem of causing a change with time in the spray shape and the injection flow rate.

An object of the present invention is to reduce the fuel remaining in the vicinity of the injection nozzle outlet, thereby preventing deposits generated in the injection nozzle and in the vicinity of the injection nozzle outlet, so that there is no change with time in the spray shape and the injection flow rate. Is to provide.

The object of the present invention is achieved, for example, by forming a predetermined spot facing on the outlet side of the injection nozzle and providing a step portion between the nozzle and the spot facing.

According to the present invention, it is possible to improve the exhaust performance and the fuel consumption performance by preventing the deposit generated in the injection nozzle and in the vicinity of the injection nozzle outlet and realizing the fuel injection device in which the spray shape and the injection flow rate do not change with time. An internal combustion engine can be realized.

Issues, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is sectional drawing which shows the Example of the fuel injection valve which concerns on this invention. It is sectional drawing to which the vicinity of the valve body front-end | tip of the fuel injection valve which concerns on 1st Example of this invention was expanded. It is sectional drawing to which the injection nozzle vicinity of FIG. 2 was expanded (1st Example). FIG. 4 is a diagram illustrating a mechanism for reducing residual fuel in the vicinity of the injection nozzle outlet in the injection nozzle of FIG. 3. It is a residual fuel distribution near the injection nozzle outlet in the conventional injection nozzle structure. In the conventional injection nozzle structure, it is a residual fuel distribution in the vicinity of the injection nozzle outlet when a concave portion is provided on the orifice cup surface located at the downstream outlet of the spot facing portion. In 1st Example of this invention, it is the example which used the R part of the downstream exit of the spot facing part as the chamfering part (2nd Example). In the first embodiment of the present invention, the R portion at the downstream outlet of the spot facing portion is eliminated (third embodiment). In the first embodiment of the present invention, the concave portion provided on the surface of the orifice cup located at the downstream outlet of the spot facing portion is removed (fourth embodiment). In the first embodiment of the present invention, it is an example in which the outer peripheral side end face of the concave portion provided on the orifice cup surface located at the downstream outlet of the spot facing portion is configured by a curved surface (fifth embodiment). In 1st Example of this invention, it is an example which formed the hollow in the outer peripheral side of the recessed part provided in the orifice cup surface located in the downstream exit of a spot facing part (6th Example). The first embodiment of the present invention is an example in which the spot facing portion is asymmetric with respect to the injection nozzle central axis (seventh embodiment). In 1st Example of this invention, it is an example which used the side wall of the spot facing part as the curved surface (8th Example).

A fuel injection valve according to a first embodiment of the present invention will be described below with reference to FIGS.
(Explanation of basic operation of injection valve)
In FIG. 1, fuel is supplied from a fuel supply port 112 and is supplied into the fuel injection valve. The electromagnetic fuel injection valve 100 shown in FIG. 1 is a normally closed electromagnetic drive type, and when the coil 108 is not energized, the valve body 101 is urged by the spring 110 and pressed against the seat member 102. The fuel is sealed. At this time, in the in-cylinder fuel injection valve, the supplied fuel pressure is in the range of about 1 MPa to 35 MPa.

FIG. 2 is an enlarged cross-sectional view of the vicinity of the injection nozzle provided at the tip of the valve body. When the fuel injection valve is in the closed state, the valve body 101 keeps the fuel seal by contacting the valve seat surface 203 formed of a conical surface provided on the seat member 102 joined to the nozzle body 104 by welding or the like. It is like that. At this time, the contact portion on the valve body 101 side is formed by the spherical surface 202, and the contact between the conical valve seat surface 203 and the spherical surface 202 is in a substantially line contact state. When the coil 108 shown in FIG. 1 is energized, a magnetic flux density is generated in the core 107, the yoke 109, and the anchor 106 constituting the magnetic circuit of the solenoid valve, and the magnetic attraction force is generated between the core 107 and the anchor 106 having a gap. Produce. When the magnetic attractive force becomes larger than the force of the biasing force of the spring 110 and the aforementioned fuel pressure, the valve body 101 is attracted to the core 107 side by the anchor 106 while being guided by the guide member 103 and the valve body guide 105 to open the valve. It becomes a state.

When the valve is opened, a gap is created between the valve seat surface 203 and the spherical surface portion 202 of the valve body, and fuel injection is started. When the fuel injection is started, the energy given as the fuel pressure is converted into kinetic energy and injected to the fuel injection nozzle 201.

FIG. 3 is an enlarged cross-sectional view of the vicinity of the injection nozzle 201 of FIG.
(Flow, effect explanation)
FIG. 4 is a diagram illustrating a mechanism for preventing residual fuel near the injection nozzle outlet in the injection nozzle of the first embodiment. In the main injection nozzle, fuel flows into the injection nozzle 201 from the direction of the arrow 301 shown in FIG. The fuel that has passed through the injection nozzle 201 is injected into the spot facing portion 206. The fuel exits the injection nozzle 201, and at the same time, breaks into droplets and changes into a spray form. After passing through the spot facing portion, the fuel is injected into the air.

The first feature of the present embodiment is that the diameter of the spot facing 206 is formed so as to go downstream.

As a result, the outer edge of the spray coming out of the spray nozzle 201 comes into slight contact with the inner wall surface of the spot facing 206, and as a result, the cleaning 404 of the inner wall of the spot facing can be performed. It is possible to prevent foreign matter from adhering to the wall surface and residual fuel 405. Further, as a merit of forming the spot facing portion 206, even if the plate thickness of the orifice cup 102 is the same, the length of the injection nozzle 201 can be freely changed by changing the depth of the spot facing portion 206. . Since the length of the injection nozzle 201 greatly affects the spray shape, it is a great merit that the length of the injection nozzle 201 can be freely changed.

In the first embodiment, a step portion 205 is provided between the spray nozzle 201 and the spot facing portion 206, and the spray generation position is fixed by the step portion 205, thereby realizing stable spray formation with little shot variation. Is done. Further, the step 205 makes it possible to reduce fuel dripping just before the valve body 101 is closed. This is because the fuel that has been slowed down just before the valve is closed is trapped by the surface tension effect (meniscus effect) generated in the step portion 205. The width of the stepped portion 205 is smaller than the inner diameter of the injection nozzle 201 (preferably 15% or less), and a small amount of fuel is trapped.

In the first embodiment, an R portion 207 is formed at the downstream outlet of the spot facing portion 206, and

oil repellent coatings

302 and 303 are formed upstream from the R portion or the chamfered portion. Further, a recess 208 is provided for each spray nozzle 201 on the surface of the orifice cup 102 located at the downstream outlet of the spot facing 206 for each spray nozzle 201. Due to the former effect, the fuel 401 remains only in the injection nozzle, and the fuel interface is formed as in 403. Further, after the cleaning 404, when there is residual fuel in the vicinity of the exit of the spot facing portion 206 and in the concave portion 208 on the surface of the orifice cup 102, the residual fuel is caused by the surface tension effect (meniscus effect) generated in the outer edge groove portion 209 of the concave portion 208. The liquid film 402 is formed at a position away from the outlet of the spot facing 206 by being drawn toward the outer edge groove 209 of the recess 208. With the above two effects, it is possible to prevent residual fuel in the spot facing portion 206 and in the vicinity of the outlet, and it is possible to prevent deposits that change the spray shape and the injection flow rate.

The residual fuel distribution in the conventional structure will be described with reference to FIGS.
FIG. 5 shows that the nozzle hole in the tip region of the fuel nozzle has a stepped shape and the diameter of the nozzle hole in the tip portion is larger than the nozzle hole near the valve seat so that the fuel spray flow is generated in the nozzle hole tip region It prevents it from adhering to the inner wall. However, when fuel injection is repeated, the fuel scattered from the spray remains in the stepped shape portion provided in the tip region of the spray fuel nozzle hole due to the surface tension effect of the step angle portion, and finally in the nozzle hole. The interface shape of the fuel 501 is formed in the vicinity of the counterbore portion outlet as indicated by 503. As a result, there is a problem that deposits occur in the spot facing portion. In the shape of FIG. 5, the counterbore portion outlet is an edge 504. Since the fuel is attracted to the edge portion 504 due to the surface tension effect, there is a problem that a liquid film 501 of residual fuel is generated around the counterbore portion outlet and is deposited.

Further, if the oil repellent coating is continuously coated from the front end surface to the outer peripheral surface of the spot facing portion, the residual fuel generated on the inner wall of the spot facing portion cannot move to the outer peripheral surface, and there is a problem that the residual fuel further increases. is there.

FIG. 6 shows the residual fuel distribution in the case where a concave portion centered on the injection nozzle is formed on the orifice cup surface located at the downstream outlet of the spot facing portion. In this shape, the fuel remaining in the recess is trapped by the outer edge 209 of the recess and the edge 504 at the exit of the spot facing portion, so that there is a problem that the liquid film 601 grows larger than that of the liquid film 402 in FIG.

The injection nozzle structure shown in the present embodiment is described by taking a fuel injection device for a cylinder injection engine as an example, but an effect can also be obtained in a fuel injection device for a port injection engine. The same applies to the embodiments described hereinafter.

FIG. 7 shows a second embodiment. In the first embodiment of the present invention, the R portion 207 is changed to a chamfered portion 701 to facilitate the processing, and the residual fuel is the same as in the first embodiment. Can be prevented.

FIG. 8 shows a third embodiment. In the first embodiment of the present invention, the processing is facilitated by eliminating the R portion at the downstream outlet of the spot facing portion. Similarly, the effect of preventing residual fuel can be obtained. In FIG. 8, there is an edge 801 at the exit of the spot facing 206, but the edge 209 at the outer edge of the recess 208 has a larger surface tension effect (meniscus effect), so the liquid film is formed as 402 in FIG. Is done.

FIG. 9 shows a fourth embodiment, which is an example in which machining is facilitated by eliminating the recess 208 on the surface of the orifice cup. Similar to the first embodiment, the effect of preventing residual fuel in the spot facing portion is obtained. It is done.

FIG. 10 shows a fifth embodiment, in which the outer peripheral side end surface of the recess 208 on the orifice cup surface is configured by a curved surface 1001, and the effect of preventing residual fuel can be obtained as in the first embodiment.

FIG. 11 shows a sixth embodiment, which is an example in which a depression 1101 is formed on the outer peripheral side of a recess provided on the orifice cup surface located at the downstream outlet of the spot facing portion. Thereby, the effect of attracting the residual fuel in the concave portion toward the outer peripheral side of the concave portion can be strengthened, and a further effect of preventing the residual fuel can be obtained. In FIG. 11, the outer peripheral end surface of the concave portion is a curved surface, but it may be an edge shape as indicated by 209 in FIG.

FIG. 12 shows a seventh embodiment, in which the spot facing portion is asymmetric with respect to the central axis of the injection nozzle. The spray from the injection nozzle 201 is often asymmetric with respect to the central axis of the nozzle. In order to enhance the cleaning effect of the spot facing portion 206, the inner wall of the spot facing portion 206 is matched to the spray shape of the spray nozzle. Ideally, the degree of taper is changed. This shape provides a further effect of preventing residual fuel.

FIG. 13 shows an eighth embodiment. The inner wall of the spot facing portion is formed by a curved surface, and the inner wall and the R portion of the spot facing portion are processed consistently. As in the first embodiment, FIG. The effect of preventing residual fuel can be obtained.

Further, the above-described embodiment can be described as follows. That is, it has a seat part that contacts the valve body and seats the fuel and a plurality of nozzles in the seat part, and a spot facing part is formed on the outlet side of the nozzle, and the diameter of the spot facing part increases toward the downstream. And a step portion is provided between the nozzle and the spot facing portion. Also, the opening angle of the spot facing can be made different for a plurality of nozzles. Thereby, a more accurate spray shape can be designed.

DESCRIPTION OF SYMBOLS 100 ... Electromagnetic fuel injection valve 101 ... Valve body 102 ... Valve seat member 103 ... Guide member 104 ... Nozzle body 105 ... Valve body guide 106 ... Movable element 107 ... Magnetic core 108 ... Coil 109 ... Yoke 110 ... Biasing spring 111 ... Connector 112 ... Fuel supply port 201 ... Injection nozzle 202 ... Spherical surface 203 of the valve element ... Valve seat surface 204 ... Vertical axis 205 of fuel injection valve ... Stepped portion 206 ... Counterbore portion 207 ... R portion 208 ... Recessed portion 209 ... Outer edge portion 301 ... Fuel inflow direction 302 ... oil repellent coating 303 ... oil repellent coating 304 ... surface 401 without oil repellent coating ... fuel 402 in the injection nozzle ... liquid film 403 ... in the injection nozzle The liquid film interface 404 of the counterbore by fuel spray Cleaning effect of inner wall 405 ... Foreign matter adhesion to the inner wall surface of the spot facing and residual fuel 501 ... Liquid film 502 ... Residual fuel 503 in the injection nozzle and spot facing 503 ... Residual of the spot facing Fuel interface 504 ... Edge of counterbore part 601 ... Liquid film 701 ... Chamfered part 801 ... Edge 1001 of counterbore part outlet ··· Curved surface 1101 · · · A recess 1201 on the outer peripheral side .... the counterbore 1301 asymmetric with respect to the central axis of the injection nozzle .... the inner wall of the spot facing is a curved surface.

Claims

A conical seat surface that seats fuel in contact with the valve body; a plurality of fuel injection hole inlet openings in the conical seat surface; and a plurality of injection hole shafts that connect the centers of the inlet and outlet of the fuel injection hole. In an injection nozzle configured to be along different conical surfaces,
A counterbore part is formed on the outlet side of the injection nozzle, the diameter of the counterbore part is formed so as to go downstream, and a stepped part is provided between the injection nozzle and the counterbore part. A fuel injection valve characterized by that.
The injection nozzle of claim 1,
The fuel injection valve characterized in that the spot facing portion is asymmetric with respect to the central axis of the injection nozzle.
In the injection nozzle of claim 1 or claim 2,
A fuel injection valve characterized in that an oil-repellent coating is formed upstream from the downstream outlet of the spot facing portion.
In the injection nozzle of claim 1 or claim 2,
A fuel injection valve characterized in that an R portion or a chamfered portion is formed at a downstream outlet of the spot facing portion, and an oil repellent coating is formed on the upstream side of the R portion or the chamfered portion.
In the fuel injection valve according to claim 3 or 4,
A fuel injection valve characterized in that a recess centered on the injection nozzle is provided for each injection nozzle on the surface of the orifice cup positioned at the downstream outlet of the spot facing portion.
The fuel injection valve according to claim 5,
A fuel injection valve characterized in that a recess is formed on the outer peripheral side in the recess.
The fuel injection valve according to claim 1, wherein
A fuel injection valve, wherein an inner wall of a spot facing is formed by a curved surface.
The fuel injection valve according to claim 1,
The counterbore does not function as an injection nozzle, or does not function as spray shape control and flow rate control.
A seat portion that contacts the valve body and seats the fuel;
The sheet portion has a plurality of nozzles,
A counterbore part was formed on the outlet side of the nozzle, the diameter of the counterbore part was formed to increase toward the downstream, and a stepped part was provided between the nozzle and the counterbore part. A fuel injection valve characterized by.
The fuel injection valve according to claim 9, wherein
An opening angle of the spot facing differs among the plurality of nozzles.