JPWO2017064986A1 - Fuel injection device - Google Patents

Abstract

Provided is a fuel injection device capable of reducing the manufacturing cost while improving the sealing reliability of a valve body and a seat portion. The fuel injection device includes a valve body 41 that contacts and seals the orifice cup 7 (seat member), a mover 40 that is joined and integrated with the valve body 41, and a movable core 4 that drives the mover 40. . The mover 40, the valve body 41, and the movable core 4 are configured so that the hardness of the mover 40 is closer to the hardness of the movable core 4 than the hardness of the valve body 41 or the orifice cup 7.

Description

  The present invention relates to a fuel injection device.

  In a direct injection type engine in which fuel is directly injected into the combustion chamber, the fuel injection valve (fuel injection device) is not normally operated except for the injection timing controlled by the engine control unit. Called period). However, since the fuel pressure inside the fuel injection valve remains high during the non-operation period, the fuel leaks into the combustion chamber if the oil tightness of the seat portion is poor. Therefore, improvement of the oil tightness performance in the seat portion of the fuel injection valve is required.

On the other hand, as the regulation value of exhaust performance becomes stricter, further atomization is required to improve the mixture combustion, and the fuel pressure tends to increase year by year. For this reason, the impact force of the valve body on the seat portion increases, and the durability performance must be taken into consideration. Under such circumstances, these two parameters are generally in conflict with each other, while the demand for improving the oil tightness of the seat and providing a fuel injection valve at a low cost is increasing.
Therefore, it is necessary to narrow down the functions of the movable member to the minimum necessary and to solve two conflicting relationships.

  In this regard, a fuel injection valve that can easily adjust the stroke of the mover is known (see, for example, Patent Document 1).

JP 2007-218205 A

  In the structure described in Patent Document 1, there is a description that the movable core provided with a valve body at the tip is reciprocated by the movement of the movable core so that the movable core and the movable element are sliding members. There is no particular description of the hardness of the child. Although there is a description that the material of the mover is SUS420J2, which has good corrosion resistance, in this case, a heat treatment process is newly required to improve the corrosion resistance, and the fuel injector can be expensive.

  The objective of this invention is providing the fuel-injection apparatus which can reduce manufacturing cost, improving the sealing reliability by a valve body and a seat part.

  In order to achieve the above object, the present invention provides a valve body that contacts and seals with a seat member, a mover that is joined and integrally formed with the valve body, a movable core that drives the mover, The mover, the valve body, and the movable core are configured such that the hardness of the mover is closer to the hardness of the movable core than the hardness of the valve body or the seat member. It is a thing.

  ADVANTAGE OF THE INVENTION According to this invention, manufacturing cost can be reduced, improving the sealing reliability by a valve body and a seat part. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a longitudinal section showing the whole fuel injection valve composition concerning one embodiment of the present invention. It is a schematic diagram showing the configuration around the valve body.

  Hereinafter, the configuration and operational effects of a fuel injection valve (fuel injection device) according to an embodiment of the present invention will be described with reference to the drawings. In each figure, the same numerals indicate the same parts.

  FIG. 1 is a longitudinal sectional view showing the overall configuration of a fuel injection valve according to an embodiment of the present invention. The fuel injection valve of the present embodiment is a fuel injection valve that directly injects fuel such as gasoline into a cylinder (combustion chamber) of an engine.

  The fuel injection valve body 1 includes a hollow fixed core 2, a yoke 3 that also serves as a housing, a movable core 4, a mover 40 (plunger), and a nozzle body 5. An electromagnetic coil 6 is incorporated inside the yoke 3. The electromagnetic coil 6 is covered with a yoke 3, a resin cover 23, and a part of the nozzle body 5 while maintaining a sealing property.

  A movable core 4 is movably incorporated in the nozzle body 5. An orifice cup 7 that is a part of the nozzle body is fixed to the tip of the nozzle body 5.

  Inside the fixed core 2, a spring 8 that presses the movable core 4 against the seat portion 7B, an adjuster 9 that adjusts the spring force of the spring 8, and a filter 10 are incorporated.

  The valve body 41 of this embodiment may be a needle type or a spherical shape with a tapered tip, and has a shape that can contact a seat portion 7B on a conical surface 7A provided inside the orifice cup 7.

  In other words, the valve body 41 contacts and seals with the orifice cup 7 (seat member). In the example of FIG. 1, the valve body 41 is configured in a needle shape (substantially conical shape), but in the example of FIG. 2, the valve body 41 is configured in a spherical shape.

  As shown in FIG. 1, the fuel passage in the fuel injection valve includes an inside of the fixed core 2, a plurality of holes 13 provided in the movable core 4, a plurality of holes 14 provided in the guide member 11, and a nozzle body 5. And a conical surface 7A including the seat portion 7B.

  The resin cover 23 is provided with a connector portion 23A for supplying an exciting current (pulse current) to the electromagnetic coil 6, and a part of the lead terminal 18 insulated by the resin cover 23 is located in the connector portion 23A.

  When the electromagnetic coil 6 housed in the yoke 3 is excited by the external drive circuit (not shown) via the lead terminal 18, the fixed core 2, the yoke 3 and the movable core 4 form a magnetic circuit, and the movable core 4 Is magnetically attracted to the fixed core 2 side against the force of the spring 8. At this time, the mover 40 and the valve body 41 are separated from the seat portion 7B and are opened, and the fuel in the fuel injection valve body 1 that has been pressurized (1 MPa or more) in advance by an external high-pressure pump (not shown) It is injected from the nozzle hole 70.

  In other words, the movable core 4 drives the mover 40.

  When the excitation of the electromagnetic coil 6 is turned off, the mover 40 and the valve body 41 are pressed against the seat portion 7B side by the force of the spring 8, and the valve is closed.

  Next, the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram schematically showing the configuration around the valve body. That is, FIG. 2 shows a schematic view of the movable core 4, the movable element 40, the valve body 41, and the vicinity of the seat portion 7 </ b> B of the orifice cup 7.

  As described above, the valve body 41 may be a needle type or a spherical shape, but here, a spherical shape is shown. The movable core 4 and the movable element 40 are slidable with respect to each other, and the movable core sliding part inner diameter 4A and the movable element sliding part outer diameter 40A are set to be substantially equal or the movable element sliding part outer diameter 40A is set to be slightly smaller. ing. At this time, the hardness of the valve body 41 is configured to be greater than the hardness of the movable core 4 and the hardness of the movable element 40.

  In general, the movable core 4 is often made of soft magnetic stainless steel to constitute a magnetic circuit. The hardness (Vickers hardness) of this soft magnetic stainless steel is about Hv 150 to 200, but even if ferritic stainless steel is used. Well, it can be selected according to the usage environment of the injection valve. On the other hand, the material used for the mover 40 may be a high hardness material such as SUS420J2 (eg, Hv 540 to 650), but considering the local surface pressure (Hertz stress) of the sliding part, it corresponds to the hardness of soft magnetic stainless steel. If this is the case, the sliding portion will not be worn and the reliability will not be impaired.

  On the other hand, the valve body 41 needs to be in contact with the seat portion 7B of the orifice cup 7 in the closed state to maintain oil tightness. However, in order to ensure strength against impact force when the valve is closed, the valve body 41 and the orifice cup 7 are required. The material hardness of the sheet portion 7B is a high hardness material. The hardness in this case is about Hv 540 to 650. For example, SUS420J2 or SUS440C may be used as a heat-treated martensitic stainless steel.

  In other words, the hardness of the orifice cup 7 (sheet member) is about Hv 540 to 650. Thereby, the intensity | strength and durability with respect to an impact force can be ensured, and seal reliability can be improved.

  However, it is sufficient that the hardness of the movable element 40 is about half of Hv 180 to 300 and less than half of the hardness of the valve body 41 (Hv 540 to 650). Therefore, for example, austenitic stainless steel (SUS304 or the like) can be used as the material used for the mover 40. Even martensitic stainless steel may be used without heat treatment (high hardness treatment).

  Accordingly, the hardness of the movable element 40 is configured closer to the movable core 4 than the valve body 41, and may be configured to be less than half the hardness of the valve body 41.

  In other words, the mover 40, the valve body 41, and the movable core 4 are configured such that the hardness of the mover 40 is close to the hardness of the movable core 4 with respect to the hardness of the valve body 41 or the orifice cup 7 (seat member). To do. Since it is not necessary to perform heat treatment to increase the hardness of the mover 40, the manufacturing cost can be reduced. Here, the hardness of the mover 40 is approximately half or less of the hardness of the valve body 41 or the orifice cup 7. Thereby, the process of the needle | mover 40 becomes easy, for example.

  Further, since the mover 40 does not require the above-described heat treatment (high hardness treatment), the mover sliding portion outer diameter 40A (outer peripheral portion) does not need to be polished, and may be configured by cutting, for example.

  In other words, the outer peripheral portion of the mover 40 has a portion that is not polished, and this portion is cut. Thereby, the manufacturing cost of the needle | mover 40 can be reduced. Specifically, since a part that does not require polishing can be handled only by cutting, it is possible to reduce heat treatment, polishing equipment and processing costs before polishing, and greatly reduce the manufacturing cost of the mover 40. It becomes possible.

  Although the soft magnetic stainless steel (Hv150-200) was shown as an example of a material used for the movable core 4, it can also be used for a material with a relatively high hardness (-Hv360).

  In other words, the hardness of the movable core 4 may be about Hv 150 to 360. Further, the hardness of the movable element 40 is larger than the hardness of the movable core 4, and the hardness of the valve body 41 or the orifice cup 7 (sheet member) is larger than the hardness of the movable element 40. Thereby, hardness can be set according to the stress generated by the impact force between the valve body 41 and the orifice cup 7. Therefore, heat treatment (high hardness treatment) can be minimized, and the manufacturing cost can be reduced while improving the seal reliability.

  The valve body 41 is coupled in the vicinity of the tip of the movable element 40, and may be constituted by caulking, press-fitting, shrink fitting, or the like, or may be welded. In other words, the mover 40 is joined to the valve body 41 and formed integrally. The valve body 41 is constituted by a member different from the mover 40. Thereby, when the shape of the orifice cup 7 is changed, only the valve body 41 needs to be changed. Moreover, the valve body 41 and the mover 40 which are formed of different members are configured by, for example, welding joint. Thereby, the valve body 41 and the needle | mover 40 can be fixed easily.

  As described above, according to the present embodiment, it is possible to reduce the manufacturing cost while improving the sealing reliability of the valve body and the seat portion. In other words, it is possible to provide an inexpensive fuel injection valve having a structure in which the movable core and the movable element can slide relative to each other without impairing the reliability of the sliding portion. Further, since the valve body uses a material having higher hardness than the fixed core and the mover, the reliability of the seat portion and the seat oil tightness can be improved.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve main body 2 ... Fixed core 3 ... Yoke 4 ... Movable core 40 ... Movable element (plunger)
41 ... Valve body 5 ... Nozzle body 6 ... Electromagnetic coil 7 ... Orifice cup 70 ... Injection hole (orifice)
7A ... Conical surface 7B ... Seat 8 ... Spring 9 ... Adjuster 10 ... Filter 11, 12 ... Guide member 13 ... Multiple holes 14 provided in movable core ... Multiple holes 18 provided in guide member ... Lead terminal 23 ... Resin cover

Claims (11)

A valve body that contacts and seals the seat member;
A mover integrally formed with the valve body;
In a fuel injection device comprising a movable core that drives the mover,
The fuel injection, wherein the mover, the valve body, and the movable core are configured so that the hardness of the mover is close to the hardness of the movable core with respect to the hardness of the valve body or the seat member. apparatus. The fuel injection device according to claim 1,
The fuel injector is characterized in that the hardness of the movable element is approximately half or less of the hardness of the valve body or the seat member. The fuel injection device according to claim 1,
The fuel injection device according to claim 1, wherein the outer peripheral portion of the mover has a portion that is not polished. The fuel injection device according to claim 1,
A portion of the outer periphery of the mover that is not polished is cut. The fuel injection device according to claim 1,
The fuel injector has a hardness of the mover of about Hv 180 to 300. The fuel injection device according to claim 1 or 5,
The fuel injector according to claim 1, wherein the movable core has a hardness of about Hv150 to 360. The fuel injection device according to claim 1 or 5,
The fuel injection device according to claim 1, wherein the sheet member has a hardness of about Hv 540 to 650. The fuel injection device according to claim 1,
The fuel injection device according to claim 1, wherein the valve body is formed of a member different from the movable element. The fuel injection device according to claim 8, wherein
The fuel injection device according to claim 1, wherein the valve body has a spherical shape. The fuel injection device according to claim 8 or 9,
The fuel injection device according to claim 1, wherein the valve body and the mover formed of different members are formed by welding. The fuel injection device according to claim 1,
The fuel injector according to claim 1, wherein the hardness of the movable element is larger than the hardness of the movable core, and the hardness of the valve body or the seat member is larger than the hardness of the movable element.

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