JP2009264129A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection device for an internal combustion engine maintaining good sealing performances with a fuel injection device mounting hole by a seal ring fitted in an annular seal groove at a tip part of a fuel injection device even if the seal ring deteriorates by age and not damaging the seal ring when the tip part is inserted in the attachment hole. <P>SOLUTION: An elastic member 9 pressing the seal ring 8 providing seal performances with the fuel injection device mounting hole 6a radially outward by elastic force is provided in the annular seal groove 7 at the tip part of the fuel injection device 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection device for an internal combustion engine.

  In particular, in a fuel injection device that directly injects fuel into a cylinder, a seal mechanism for preventing leakage of combustion gas is required between the periphery of the tip of the fuel injection device and the fuel injection device mounting hole. . As such a sealing mechanism, generally, an annular seal groove is formed at the tip of the fuel injection device, and the outer peripheral portion of the seal ring fitted in the annular seal groove is brought into contact with the fuel injection device mounting hole. I am doing so. Thus, the seal ring is compressed to provide a sealing property between the seal ring and the fuel injection device mounting hole, thereby preventing combustion gas leakage from the cylinder.

  The seal ring is generally made of a resin, and when creep occurs due to aging deterioration and the elasticity is lowered, the above-mentioned sealability is impaired and combustion gas leaks. In order to improve this problem, an annular protrusion is provided at the center of the annular seal groove of the fuel injection device, and the center of the seal ring is greatly compressed and deformed, or the annular seal groove is tapered so as to become shallow toward the outside, It has been proposed that the seal ring is moved outward by the combustion gas pressure and greatly compressed and deformed as the elasticity of the seal ring is lost (see, for example, Patent Document 1).

JP 2002-285939 A JP 10-318093 A JP-A-11-72061

  In a seal structure in which an annular protrusion is provided in the center of the annular seal groove of the fuel injection device so that the seal ring is greatly compressed and deformed, the seal ring also generates creep due to deterioration over time and the sealing performance deteriorates.

  Further, in the seal structure in which the annular seal groove of the fuel injection device is tapered, the width of the annular seal groove is sufficiently larger than the width of the seal ring so that the aged seal ring can move outward. Therefore, when attaching the annular fuel injection device, the seal ring that has not deteriorated over time may not move due to friction with the attachment hole, and only the tip of the fuel injection device may be inserted into the attachment hole. As a result, the seal ring that has not deteriorated over time may move to the outside relative to the annular seal groove, and the inner diameter may be excessively enlarged and damaged.

  Accordingly, an object of the present invention is to maintain a good sealing property with the fuel injection device mounting hole even when the seal ring is deteriorated over time by the seal ring fitted into the annular seal groove at the tip of the fuel injection device. Another object of the present invention is to provide a fuel injection device for an internal combustion engine that does not damage the seal ring when the tip portion is inserted into the mounting hole.

  In the fuel injection device for an internal combustion engine according to the first aspect of the present invention, the sealing performance between the fuel injection device mounting hole is provided by the seal ring fitted in the annular seal groove formed at the tip portion. In the fuel injection device, an elastic member for pressing the seal ring radially outward by an elastic force is provided in the annular seal groove.

  A fuel injection device for an internal combustion engine according to a second aspect of the present invention is the fuel injection device for an internal combustion engine according to the first aspect, wherein the elastic member is a C-ring.

  The fuel injection device for an internal combustion engine according to claim 3 according to the present invention is the fuel injection device for internal combustion engine according to claim 2, wherein the width of the elastic member and the width of the seal ring are substantially equal. To do.

  According to the fuel injection device for an internal combustion engine according to the first aspect of the present invention, the sealing performance between the fuel injection device mounting hole is provided by the seal ring fitted in the annular seal groove formed at the tip portion. In the fuel injection device, since an elastic member that presses the seal ring radially outward is provided in the annular seal groove, even if the seal ring deteriorates over time and its elasticity decreases. The seal ring is pressed by the fuel injection device mounting hole by the elastic member, and good sealing performance can be maintained. Further, the annular seal groove is not tapered, and the inner diameter of the seal ring is not excessively enlarged and damaged when the tip portion is inserted into the mounting hole.

  According to a fuel injection device for an internal combustion engine according to a second aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, the elastic member is a C-ring and is sealed by such a simple elastic member. Even if the ring deteriorates over time, good sealing performance can be maintained.

  According to the fuel injection device for an internal combustion engine according to claim 3 of the present invention, in the fuel injection device for internal combustion engine according to claim 2, the width of the elastic member and the width of the seal ring are substantially equal. Thereby, the seal ring can be entirely pressed against the fuel injection device mounting hole by the elastic force of the elastic member, and a better sealing performance can be provided.

  FIG. 1 is a schematic sectional view showing a tip portion of a fuel injection device for an internal combustion engine according to the present invention. In the figure, 1 is a main body of the fuel injection device, 2 is a fuel passage in the main body 1, and 3 is a fuel reservoir formed at the tip of the fuel passage 2. An injection hole 4 communicating with the fuel reservoir 3 is formed in the main body 1.

  Reference numeral 5 denotes a valve body. As shown in FIG. 1, the seal portion at the tip of the valve body 5 is brought into contact with the frustoconical sheet portion of the main body 1, so Is cut off, and the injection of the high-pressure fuel in the fuel passage 2 through the nozzle hole 4 is stopped. Further, when the valve body 5 is lifted and the seal portion at the tip of the valve body 5 is separated from the seat portion of the main body 1, the fuel passage 2 and the fuel reservoir 3 communicate with each other, and the fuel passage 2 is connected via the injection hole 4. The high-pressure fuel inside is injected.

  This fuel injection device, for example, directly injects fuel into a cylinder, 6 is, for example, a cylinder head to which this fuel injection device is attached, and 6a is an attachment hole formed in the cylinder head. In such a configuration, it is necessary to prevent the high-temperature and high-pressure combustion gas in the cylinder from leaking through the gap between the mounting hole 6a and the tip of the fuel injection device main body 1.

  For this purpose, an annular seal groove 7 is formed at the tip of the main body 1, and a seal ring 8 made of Teflon (registered trademark) resin is fitted into the annular seal groove 7, so that the seal ring 8 extends in the thickness direction. By compressing, the sealing property between the seal ring 8 and the mounting hole 6a is provided. FIG. 2 is an enlarged view of the vicinity of the annular seal groove 7 in FIG. 1. As shown in FIG. 2, the sealing performance between the seal ring 8 and the annular seal groove 7 of the main body 1 is as follows. When pressed outward by pressure, the seal ring 8 is also compressed in the width direction, and is provided by the contact between the outer end surface 8 a extending in the thickness direction of the seal ring 8 and the outer side surface 7 a of the annular seal groove 7. The

  The sealing performance between the seal ring 8 and the annular seal groove 7 is maintained well even if the pressure in the cylinder always acts on the seal ring 8 and the elasticity of the seal ring 8 is lowered due to deterioration over time. The However, the sealing property between the seal ring 8 and the mounting hole 6a is that the seal ring 8 is deteriorated over time only by fitting the seal ring 8 into the annular seal groove 7 and compressing the seal ring 8 in the thickness direction. If the elasticity of is reduced, it will be easily damaged.

  In order to improve this problem, in this fuel injection device, an annular groove 7c is formed at the center of the bottom surface 7b of the annular seal groove 7, and an elastic member 9 is disposed in the annular groove 7c. The elastic member 9 is, for example, a metal C-ring shown in FIG. 3, arranged in the annular groove 7 c so as to reduce the diameter, and is brought into contact with the inner surface 8 b of the seal ring 8. Thereby, the elastic member 9 presses the seal ring 8 radially outward by elastic force, and even if the seal ring 8 is deteriorated with age and its elasticity is lowered, a good gap between the seal ring 8 and the mounting hole 6a is obtained. Sealability can be maintained.

  Even if the elastic member 9 disposed in the annular groove 7c has the C-ring shape shown in FIG. 3 in which both end faces of the cut coincide with the plane on the central axis, both end faces of the cut are respectively in relation to the central axis. The C-ring shape shown in FIG. 4 on an oblique plane may be used.

  Further, as shown in FIG. 5 which is a modified example of FIG. 1, the width of the C-ring-shaped elastic member 9 ″ is substantially equal to the width of the seal ring 8 ′ and is annular so as to fit in the annular seal groove 7 ′. Even if it is slightly smaller than the width of the seal groove 7 ′, the seal ring 8 ′ is pressed radially outward by the elastic force of the elastic member 9 ″ as described above, and the seal ring 8 ′ deteriorates with age and becomes elastic. Even if it falls, the favorable sealing performance between seal ring 8 'and the attachment hole 6a can be maintained.

  With such a configuration, it is not necessary to separately process the annular groove 7c for the elastic member as shown in FIG. 1 in the annular seal groove 7 ′ of the main body 1, and the elastic member 9 ″ having substantially the same width can be used. Since the entire seal ring 8 ′ is pressed radially outward by the elastic force, it is possible to provide better sealing performance as compared with the embodiment of FIG. 1.

  In the case of the modification shown in FIG. 5, in order to provide a good sealing performance between the seal ring 8 ′ and the annular seal groove 7 ′, the depth of the annular seal groove 7 ′ is set to the thickness of the elastic member 9 ″. The contact area between the outer end surface extending in the thickness direction of the seal ring 8 ′ and the outer side surface of the annular seal groove 7 ′, which is deeper than the annular seal groove 7 of the embodiment of FIG. It is desirable to have the same form.

  The elastic member for pressing the seal ring radially outward is not limited to the C-ring shape. For example, a plurality of (for example, four or six) small coil springs are disposed at substantially equal angular intervals on the fuel injection device main body. The annular seal groove may be radially arranged so that the seal ring is pressed radially outward by the axial elastic force of each coil spring.

It is a schematic sectional drawing which shows the front-end | tip part of the fuel-injection apparatus of the internal combustion engine by this invention. FIG. 2 is an enlarged view of the vicinity of an annular seal groove in FIG. 1. It is a perspective view which shows an elastic member. It is a perspective view which shows another elastic member. It is a figure which shows the modification of the fuel-injection apparatus of the internal combustion engine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 4 Injection hole 5 Valve body 6a Mounting hole 7, 7 'Annular seal groove 8, 8' Seal ring 9, 9 ', 9 "Elastic member

Claims (3)

  In the fuel injection device in which a sealing property between the fuel injection device mounting hole is provided by a seal ring fitted in an annular seal groove formed at a distal end portion, the seal ring is provided in the annular seal groove. A fuel injection device for an internal combustion engine, characterized in that an elastic member that presses radially outward by an elastic force is provided.   The fuel injection device for an internal combustion engine according to claim 1, wherein the elastic member is a C-ring.   The fuel injection device for an internal combustion engine according to claim 2, wherein the width of the elastic member and the width of the seal ring are substantially equal.

Images