JP2008291735A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device which can significantly alleviate the problem of chips being generated when a coil spring is secured by pressure welding in a cylinder body which functions as a fuel passage. <P>SOLUTION: A cylinder body 1, with the exception of a portion where a fuel filter 34 is installed, comprises a smaller inside diameter section 11 at the downstream where the fuel filter 34 is installed, and a larger inside diameter section 12 located at the downstream of the smaller inside diameter section 11, while a coil spring 2 has a tightly winding section 21 and 22 each at the end of the spring winding section 23 located halfway of the cylinder body, one being press-fitted into the smaller inside diameter section 11, the other being welded on the top of the valve needle 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection device, and more particularly to a fuel injection device suitable for an internal combustion engine such as an automobile engine.

  In a conventional fuel injection device for an internal combustion engine, an adjustment sleeve is press-fitted into the spring chamber opening, a spring acting on the valve closing member is supported by the adjustment sleeve, and the adjustment sleeve is inserted into the guide member. The press-fitting depth defines the spring force of the spring. However, when the adjusting sleeve is press-fitted, chips are generated in the adjusting sleeve and the guide member, and there is a risk that the chips may be damaged by the chips.

  In order to solve the above-mentioned problem, it is provided with a valve closing member that cooperates with a valve seat and a return spring disposed in a spring chamber opening from claim 1 of Patent Document 1 described later, The return spring is a type in which the valve closing member is elastically moved so as to move in the direction of the valve seat, and the return spring is press-fitted into the spring chamber opening portion, and the spring chamber opening is caused by the radially directed stress. Valves held in the section are conventionally known. Further, from claim 3 of Patent Document 1, as the return spring, a spring active region facing the valve closing member and having a diameter smaller than the diameter of the spring chamber opening, and a position opposite to the valve closing member. In the prior art, a cylindrical tightening region having a diameter larger than that of the spring chamber opening is known.

According to the technique of Patent Document 1, since the adjustment sleeve used for supporting the spring and adjusting the spring force can be omitted, the generation of the chips based on the press-fitting of the adjustment sleeve and the risk of the valve being damaged by the chips. Is prevented.
Incidentally, also in the valve of Patent Document 1, when the return spring is inserted and installed in the spring chamber opening portion, the outer diameter of the return spring before the press-fitting portion is larger than the inner diameter of the spring chamber opening portion, In addition, since the press-fitting portion needs to be press-fitted in the spring chamber opening portion so that all or at least most of the return spring is accommodated in the spring chamber opening portion, there is a problem of chip generation in the whole of the press-fitting progression. Still elicited.
Further, the return spring described in claim 3 of Patent Document 1 has a shape in which the diameters of the spring active region and the tightening region are different from each other. Therefore, the manufacture thereof is complicated and the production yield is low, so that the mass production is difficult. There is a problem that it becomes unsuitable and consequently expensive.

Reality 6-9417 (Claims 1 and 3)

  In view of the above-mentioned problems in the prior art, the present invention greatly reduces the problem of chip generation when the coil spring is pressed and fixed in a cylinder functioning as a fuel passage, and is high in yield and inexpensive. It is an object of the present invention to provide a fuel injection device that can use a coil spring that can be mass-produced.

  The above-described problems include a valve needle that opens and closes a fuel passage hole provided in a valve seat, an electromagnet device that moves the valve needle in a direction in which the fuel passage hole opens, a cylinder that functions as a fuel passage, and the cylinder The fuel injection device includes a coil spring that moves the valve needle in a direction in which the fuel passage hole is closed, and the inner diameter of the cylindrical body is such that one end of the coil spring is at the end of the cylindrical body. The problem is solved by a fuel injection device characterized in that it is larger than the outer diameter of the coil spring on the downstream side of the fuel flow at the location where it is pressure-fixed to the inner wall.

  In the fuel injection device according to the present invention, the inner diameter of the cylindrical body is larger than the outer diameter of the coil spring on the downstream side of the fuel flow at a position where one end of the coil spring is pressed against the inner wall of the cylindrical body. Therefore, it is possible to mount the coil spring by inserting a coil spring from the valve needle side end of the cylinder and fixing the one end of the coil spring to the small inner diameter portion of the cylinder by pressure contact. In the period up to the press-contact fixing, only the one end is in contact with the inner diameter of the cylindrical body with high strength, and the remaining part is in contact with the inner wall of the cylindrical body even if it is lightly touched. Therefore, the problem of chip generation is greatly reduced. In addition, since the inner diameter of the cylindrical body is as described above, in the present invention, it is not necessary to change the outer diameter of the coil spring as in Patent Document 1, in other words, the same outer diameter over the entire length. The coil spring can be easily manufactured and can be mass-produced at low cost.

Embodiment 1 FIG.
Hereinafter, the present invention will be described in detail with reference to embodiments. In the following drawings, the same portions are denoted by the same reference numerals. 1 to 3 are diagrams for explaining the first embodiment of the present invention. FIG. 1 is a schematic sectional view including a partly non-sectional view of the whole of the first embodiment, and FIG. FIG. 3 is a front view of a coil spring employed in the first embodiment.

  1 to 3, the fuel injection device of the first embodiment has the same structure as the valve of Patent Document 1 except for the feature of the present invention. With reference to the description of 1, the following description will be made only for the portions other than the portions characterized by the present invention, and the characteristic portions of the present invention will be described in detail. In the description of FIGS. 1 to 3, the upstream side in the fuel flow direction is referred to as “upper” or “upper side”, and the downstream side is referred to as “lower” or “lower”.

  In the fuel injection device according to the first embodiment, a cylindrical body 1, an intermediate member 31, and a nozzle holder 32 that function as a fuel path and also as a magnetic pole along the central axis A and in the fuel flow direction are cascaded. It is connected. In the cylinder 1, a fuel filter 34 and a coil spring 2 are installed from above, and a cylindrical movable body 33 is installed inside the intermediate member 31 and the nozzle holding body 32. ing. In FIG. 1, the coil spring 2 is shown in a front view for easy understanding.

  A valve seat 42 having a valve needle 4 and a fuel passage hole is installed in the nozzle holder 32, and the valve seat 42 is fixed to the inner wall at the lower end of the nozzle holder 32 by welding or the like. A spherical valve body 41 that opens and closes the fuel passage hole provided in the valve seat 42 is fixed to the lower end of the valve needle 4 by welding or the like, and the upper top surface thereof is welded to the lower end of the coil spring 2 or the like. Further, the upper outer surface is fixed to the inner wall surface of the movable body 33 by welding or the like. The coil spring 2 always acts so that the valve needle 4 is always moved downward, that is, the fuel passage hole of the valve seat 42 is closed by the valve body 41.

  An electromagnet device 5 is installed outside the cylinder 1, and the electromagnet device 5 moves the movable body 33 upward, that is, the valve needle 4 upward, and the valve body 41 moves away from the valve seat 42. It acts to open the fuel passage hole of the seat 42. The electromagnet device 5 may be a conventionally known or well-known device, for example, the one described in Patent Document 1 described above. The cylindrical body 1, the intermediate member 31, the nozzle holding body 32, and the electromagnet device 5 are covered and protected by a resin coating 7 via a metallic protective member 6. Reference numeral 8 denotes an electrical plug connection.

  Next, the cylinder 1 and the coil spring 2 will be described in detail. The cylindrical body 1 is different from the cylindrical body in Patent Document 1 (see the inner magnetic pole 3), and its inner diameter is downstream of the location where the fuel filter 34 is inserted, apart from the location where the fuel filter 34 is inserted. Then, it is comprised from the small internal diameter part 11 and the large internal diameter part 12 provided in the downstream of the small internal diameter part 11. FIG. On the other hand, as shown in FIG. 3, the coil spring 2 has densely wound portions 21 and 22 at both ends thereof, and a spring wound portion 23 that performs a spring action between them.

  The densely wound portion 21, the closely wound portion 22, and the spring wound portion 23 may be formed of a steel wire that can perform a spring function, such as a brass wire or a spring steel wire, and in a state before being inserted into the cylindrical body 1. As shown in FIG. 3, even if there are variations that may occur in the manufacture of the spring, they have substantially the same outer diameter. One of the densely wound portion 21 and the densely wound portion 22 is fixed by press-fitting into the small inner diameter portion 11 of the cylinder 1, and the other is welded, for example, to the above-described top portion of the valve needle 4. In the present invention, the side to be welded to the top of the valve needle 4 does not have to be a tightly wound portion like the spring end side 46 on the lower end side of the return spring 43 shown in Patent Document 1, When assembling the fuel injection device according to the first embodiment, it is necessary to select which of the tightly wound portion 21 and the densely wound portion 22 of the coil spring 2 is the press-fitting side to the small inner diameter portion 11. Since there is no possibility of the selection process being omitted, the technique of Patent Document 1 may cause a defective product due to a selection error, whereas the present invention has a great advantage that the problem of the defective product is completely eliminated. is there.

  In the following description, it is assumed that the densely wound portion 21 is a press-fitting side to the small inner diameter portion 11 of the cylindrical body 1 and the densely wound portion 22 is a welded side with the valve needle 4. As the number of dense windings in the densely wound portions 21 and 22, 3 windings are illustrated in FIGS. 1 and 2, and 4 windings are illustrated in FIG. 3. In the present invention, the densely winding portions 21 are press-fitted into the small inner diameter portion 11. As long as it is possible and can be stably anchored to the inner diameter portion 11 after press-fitting, the number of dense windings is not particularly limited, but is generally 2 to 10 windings. In consideration of cost and handleability, it is preferably 2 to 5 rolls. The densely wound portion 21 is compressed by being press-fitted into the small inner diameter portion 11 and, after the press-fitting, is stably anchored to the inner diameter portion 11 by a repulsive force based on the compression, as described above. If the outer diameter of the winding portion 21 is too small, the repulsive force based on the compression after the press-fitting is poor and stable mooring at the inner diameter portion 11 is not achieved, while the outer diameter of the tightly wound portion 21 before the press-fitting is small. If it is excessively large, it is advantageous in terms of stable mooring, but there are problems that it is difficult to press-fit or that the amount of chips generated increases during press-fitting. Therefore, the outer diameter of the densely wound portion 21 before press-fitting is preferably 1.01 to 1.2 times, particularly 1.05 to 1.1 times the inner diameter of the inner diameter portion 11. Moreover, although the full length of the closely wound part 21 may be press-fitted into the small inner diameter part 11, as long as stable mooring is achieved, it may be 1 part instead of the full length. In general, at least 50%, particularly at least 80% of the entire length of the densely wound portion 21 is preferable from the viewpoint of stable mooring.

  Regarding the shape of the end surfaces of the densely wound portion 21 and the closely wound portion 22, it may be flat or uneven on the side press-fitted into the small inner diameter portion 11, but the side welded to the top of the valve needle 4. From the viewpoint of ease of welding and welding stability, it is preferable to be flat or close to it. Therefore, it is preferable that both end surfaces of the densely wound portion 21 and the densely wound portion 22 are flat or close to each other in order to omit the above-described selection step. Such a flat state can be obtained by grinding with a normal grinding means such as a grinder or a scissors.

  Next, the effect of the present invention will be described in comparison with the case of Patent Document 1. In the case of Patent Document 1, the large inner diameter portion 12 in the present invention does not exist, and only the portion corresponding to the small inner diameter portion 11 of the present invention. Since it does not exist, in order to insert the entire length of the coil spring 2 into the inner magnetic pole 3 (corresponding to the cylindrical body 1 of the present invention) of Patent Document 1, an end portion 59 (main book) having an outer diameter larger than the inner diameter of the inner magnetic pole 3 is used. It is necessary to press fit a distance corresponding to the entire length of the coil spring 2, during which the inner wall of the inner magnetic pole 3 is scraped by the end 59. The amount of chips generated increases. In contrast, in the present invention, the length by which the coil spring 2 is press-fitted into the cylindrical body 1 is only about the length of the densely wound portion 21 or the closely wound portion 22 of the present invention. Becomes much smaller.

  As understood from the above description, the inner diameter of the large inner diameter portion 12 in the present invention may be a size that allows the above-described coil spring 2 to be inserted, and the close winding portion 21, the close winding portion 22, the spring winding. What is necessary is just a magnitude | size which does not generate | occur | produce a chip substantially in the insertion process of the coil spring 2 comprised from the part 23. FIG. Further, even when one part of the coil spring 2 contacts the inner wall surface of the large inner diameter part 12 when the coil spring 2 passes through the large inner diameter part 12, such contact causes substantial generation of chips. If there is no. Therefore, the inner diameter of the large inner diameter portion 12 is 1.05 to 1.5 times the outer diameter of the coil spring 2 or, if the coil spring 2 has a maximum outer diameter portion, the outer diameter of the maximum outer diameter portion. In particular, 1.1 to 1.2 times is preferable.

  As mentioned above, although this invention was demonstrated by Embodiment 1, this invention is not limited to Embodiment 1, and the various deformation | transformation form according to the solution subject of this invention and the mind of a solution means is included. For example, the coil spring 2 may have a densely wound portion only at one end, and the spring wound portion 23 may have an outer diameter smaller than the outside diameter of the densely wound portion like the return spring 43 in Patent Document 1. .

  The fuel injection device of the present invention is likely to be used for an internal combustion engine such as an automobile engine.

FIG. 2 is a schematic cross-sectional view including a partial non-sectional view of the first embodiment. FIG. 2 is an enlarged view of a part of FIG. 2 is a front view of a coil spring employed in Embodiment 1. FIG.

Explanation of symbols

A: central axis, 1: cylindrical body, 11: small inner diameter portion, 12: large inner diameter portion, 2: coil spring,
21: Closely wound portion, 22: Closely wound portion, 23: Spring wound portion, 31: Intermediate member, 32: Nozzle holder,
33: movable body, 34: fuel filter, 4: valve needle, 41: valve body, 42: valve seat,
5: Electromagnet device, 6: Protective member, 7: Resin coating, 8: Electrical plug connection.

Claims (5)

  A valve needle that opens and closes a fuel passage hole provided in a valve seat; an electromagnet device that moves the valve needle in a direction in which the fuel passage hole is opened; a cylinder that functions as a fuel passage; A fuel injection device including a coil spring that moves the valve needle in a direction in which the fuel passage hole is closed, wherein an inner diameter of the cylindrical body is fixed by pressure contact with an inner wall of the cylindrical body. A fuel injection device characterized in that the outer diameter of the coil spring is larger on the downstream side of the fuel flow at a location where   2. The fuel injection device according to claim 1, wherein the coil spring is formed of a spring steel wire, and a portion that is press-fixed to the inner wall of the cylindrical body is closely wound.   The fuel injection device according to claim 2, wherein both ends of the coil spring are closely wound.   The fuel injection device according to any one of claims 1 to 3, wherein the coil spring has the same outer diameter over the entire length.   2. The inner diameter of the cylindrical body on the downstream side of the fuel flow is such that chips are not generated on the side wall surface on the downstream side of the fuel flow even when the coil spring is inserted. Fuel injectors.

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