Fuel injection valve mounting structure

Abstract

To reduce the size of an adapter for assembling a fuel injection valve into an insertion hole.SOLUTION: A fuel injection valve 20 is attached via an adapter 30 to an insertion hole 40 provided in a cylinder head 11. A male screw is formed on an outer peripheral surface of an adapter 30 at a portion into which a tip region on an injection hole side of the fuel injection valve 20 is inserted. The insertion hole 40 is also provided with a female screw into which the male screw of the adapter 30 is screwed. Then, a portion where the male screw and female screw are screwed has a seal structure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mounting structure for a fuel injection valve. [Background technology]

[0002] In the internal combustion engine described in Patent Document 1, a fuel injection valve is attached to an insertion hole formed in a cylinder head via an adapter. Also, a seal structure consisting of a groove for a seal member provided on the outer circumferential surface of the adapter and a seal member accommodated in this groove is adopted to ensure sealing between the insertion hole and the adapter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-267378 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a groove for a seal member is provided on the outer peripheral surface of the adapter, the adapter is increased in size in the radial direction by the wall thickness required to form the groove. [Means for solving the problem]

[0005] The fuel injection valve mounting structure that solves the above problem is a fuel injection valve mounting structure that is mounted via an adapter to an insertion hole provided in a cylinder head or an intake manifold, wherein the adapter has a male thread formed on an outer circumferential surface at a portion where a tip region of the fuel injection valve on the injection hole side is inserted, the insertion hole has a female thread into which the male thread of the adapter screws, and the portion where the male thread and the female thread screw into each other has a seal structure. Effect of the Invention

[0006] This mounting structure for the fuel injection valve makes it possible to reduce the size of the adapter for assembling the fuel injection valve into the insertion hole. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a mounting structure for a fuel injection valve according to one embodiment. [Diagram 2] FIG. 2 is an enlarged view of part A shown in FIG. [Diagram 3] FIG. 3 is a diagram showing a mounting structure of a fuel injection valve according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a mounting structure for a fuel injection valve will be described with reference to FIGS. <Fuel injection valve mounting structure> 1, an intake port 12 is formed in a cylinder head 11 of an internal combustion engine 10. In addition, an insertion hole 40 for mounting a fuel injection valve 20 that injects fuel into the intake port 12 to the cylinder head 11 is formed in the cylinder head 11.

[0009] The insertion hole 40 has a cylindrical insertion hole small diameter portion 41 that opens into the intake port 12, and a cylindrical insertion hole large diameter portion 42 that has an inner diameter larger than that of the insertion hole small diameter portion 41. A female thread is formed on the inner peripheral surface of the insertion hole small diameter portion 41. As shown in FIG. 2, the portion where the insertion hole small diameter portion 41 and the insertion hole large diameter portion 42 are connected forms a first flat seat 44 that expands in the radial direction of the insertion hole 40.

[0010] As shown in Fig. 1, the fuel injector 20 is substantially cylindrical. The fuel injector 20 has an injector small diameter portion 21 with an injection hole formed at its tip. The tip of the injector small diameter portion 21 protrudes into the intake port 12. An injector large diameter portion 22 having an outer diameter larger than that of the injector small diameter portion 21 is connected to the end of the injector small diameter portion 21 opposite to the end protruding into the intake port 12. The portion where the injector small diameter portion 21 and the injector large diameter portion 22 are connected forms a second flat seat 24 that expands in the radial direction of the fuel injector 20.

[0011] As shown in Figs. 1 and 2, a groove 50 for accommodating a gasket 51 serving as a sealing member is formed on the outer circumferential surface of the tip region of the small diameter portion 21 of the injection valve. As shown in FIG. 1, the fuel injection valve 20 is assembled into an insertion hole 40 via a cylindrical adapter 30 .

[0012] The adapter 30 is made of, for example, metal. However, the adapter 30 may be made of a material other than metal, for example, resin or ceramic. The adapter 30 has an adapter small diameter portion 31 having a male thread formed on its outer circumferential surface, and an adapter large diameter portion 32 to which an end of the adapter small diameter portion 31 is connected and which has an outer diameter larger than that of the adapter small diameter portion 31. The male thread formed on the adapter small diameter portion 31 is a thread that screws into the female thread of the insertion hole small diameter portion 41.

[0013] A seal structure is provided at the portion where the male thread of the adapter small diameter portion 31 and the female thread of the insertion hole small diameter portion 41 screw together. In this embodiment, as such a seal structure, a sealant is applied to the male thread of the adapter small diameter portion 31 and the female thread of the insertion hole small diameter portion 41.

[0014] The outer diameter of the adapter large diameter portion 32 is smaller than the inner diameter of the insertion hole large diameter portion 42. The adapter 30 is also formed with a through hole 33 that penetrates the adapter small diameter portion 31 and the adapter large diameter portion 32. The central axis of the through hole 33 and the central axis of the adapter 30 are coaxial. The injection valve small diameter portion 21 is inserted into the through hole 33.

[0015] When the fuel injection valve 20 is attached to the adapter 30, the end of the adapter large diameter portion 32 abuts against the second flat seat 24 of the fuel injection valve 20, thereby fixing the axial positional relationship between the adapter 30 and the fuel injection valve 20. The end of the fuel injection valve 20 is pressed against a delivery pipe (not shown) that distributes fuel, thereby fixing the axial position of the fuel injection valve 20.

[0016] The axial length L1 of the adapter large diameter portion 32 is set taking into consideration the amount of protrusion of the tip of the injector small diameter portion 21 into the intake port 12 and the axial length of the injector small diameter portion 21 so that the amount of protrusion is appropriate.

[0017] The length L2 in the axial direction of the adapter small diameter portion 31 is set so that the groove 50 of the injection valve small diameter portion 21 faces the inner circumferential surface of the adapter small diameter portion 31. 2, the portion where the adapter small diameter portion 31 and the adapter large diameter portion 32 are connected is a third flat seat 34 that expands in the radial direction of the adapter 30. When the adapter 30 is assembled into the insertion hole 40, the third flat seat 34 of the adapter 30 abuts against the first flat seat 44 of the insertion hole 40. This fixes the axial position of the adapter 30 relative to the insertion hole 40.

[0018] The inner diameter D1 of the through hole 33 is set to be slightly larger than the outer diameter of the injection valve small diameter portion 21 and to provide an appropriate amount of crushing margin for the gasket 51. The outer diameter D2 of the adapter small diameter portion 31, i.e., the male thread diameter, is set to a diameter that ensures a wall thickness necessary for strength.

[0019] <About action and effects> The operation and effects of this embodiment will be described. (1) A male thread is formed on the outer peripheral surface of the portion of the adapter 30 where the tip region on the injection hole side of the fuel injection valve 20 is inserted, that is, on the outer peripheral surface of the adapter small diameter portion 31. Also, a female thread is formed in the insertion hole small diameter portion 41 into which the male thread of the adapter 30 screws. The portion where the male thread and the female thread screw into has a seal structure formed by applying a sealant. Therefore, in this embodiment, the sealability between the adapter 30 and the insertion hole 40 is ensured by the screw thread having the seal structure. Therefore, the adapter 30 does not need to have a groove for a seal member, and can be made smaller than an adapter having a seal structure with such a groove.

[0020] (2) In the case of an adapter having a groove for a sealing member, there is a possibility that combustion gas or condensed water may enter the gap between the adapter and the insertion hole up to the sealing member housed in the groove, which may cause corrosion of the adapter, etc. In this regard, the adapter 30 of the present embodiment does not have such a groove, and the sealing performance is ensured by the thread of the screw having a sealing structure. Therefore, corrosion of the adapter 30, etc. can be suppressed.

[0021] (3) The male thread of the adapter small diameter portion 31 and the female thread of the insertion hole small diameter portion 41 are formed as close as possible to the portion of the insertion hole 40 that opens into the intake port 12. Therefore, compared to when the respective threads are formed at a position far from the portion of the insertion hole 40 that opens into the intake port 12, the path through which combustion gas, condensed water, and the like can enter in the gap between the adapter 30 and the insertion hole 40 is shortened. This makes it possible to suppress corrosion of the adapter 30 and other components.

[0022] (4) The fuel injection valve 20 is attached to the insertion hole 40 via the adapter 30. Therefore, by changing the adapter 30, various fuel injection valves with different shapes can be attached to the insertion hole 40. For example, it is possible to attach a fuel injection valve that injects gaseous fuel to an internal combustion engine equipped with a fuel injection valve that injects liquid fuel. It is also possible to replace an old type fuel injection valve with the latest type fuel injection valve having a different outer shape.

[0023] (5) In the case where a groove provided in the adapter and a gasket accommodated in the groove are used to ensure sealing between the adapter and the insertion hole, if various adapters are prepared, it is necessary to prepare various gaskets. In this regard, in the present embodiment, the sealing between the adapter 30 and the insertion hole 40 is ensured by the thread of the screw having a sealing structure. Therefore, when various adapters 30 are prepared, it is not necessary to prepare various gaskets.

[0024] <Examples of changes> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0025] The mounting structure shown in Fig. 3 may be adopted. That is, when the fuel used in the internal combustion engine is a fuel that is not easily corroded, such as high-octane gasoline or natural gas, the male thread of the adapter small diameter portion 31 and the female thread of the insertion hole small diameter portion 41 are omitted, and the adapter small diameter portion 31 is loosely inserted into the insertion hole small diameter portion 41, as shown in Fig. 3. Then, in order to ensure the sealing performance between the adapter 30 and the insertion hole 40, a seal structure S1 having a gasket or the like may be provided at the portion where the third flat seat 34 of the adapter 30 and the first flat seat 44 of the insertion hole 40 come into contact.

[0026] In addition, in the case where the fuel injection valve 20 does not have the groove 50 and the gasket 51, and the fuel used in the internal combustion engine is the above-mentioned fuel that is less likely to corrode, a modified example as shown in Fig. 3 can be adopted. That is, in order to ensure the sealing performance between the adapter 30 and the fuel injection valve 20, a seal structure S2 having a gasket or the like may be provided at the portion where the end of the adapter large diameter portion 32 and the second flat seat 24 of the fuel injection valve 20 come into contact.

[0027] The insertion hole 40 may be provided in the intake manifold. The small diameter insertion hole portion 41 may be provided so as to open into a wall surface of a combustion chamber provided in a cylinder head of an internal combustion engine. In this case, the fuel injection valve assembled into the insertion hole 40 becomes an in-cylinder injection valve that directly injects fuel into a cylinder of the internal combustion engine.

[0028] Other structures may be used as the seal structure for the portion where the male thread of the adapter small diameter portion 31 and the female thread of the insertion hole small diameter portion 41 screw together. For example, the male thread and the female thread may be tapered. [Explanation of symbols]

[0029] 10. Internal combustion engine 11...Cylinder head 12…Intake port 20...Fuel injector 21...Injection valve small diameter section 22…Large diameter injection valve 24…Second plane seat 30…Adapter 31...Small diameter part of adapter 32…Large diameter adapter part 33...Through hole 34...Third plane seat 40…Insertion hole 41...Small diameter insertion hole 42…Large diameter insertion hole 44...1st plane seat 50...Groove 51…Gasket

Claims

[Claim 1] A mounting structure for a fuel injection valve that is mounted via an adapter to an insertion hole provided in a cylinder head or an intake manifold, comprising: a male thread is formed on an outer circumferential surface of the adapter at a portion where a tip region of the fuel injection valve on an injection hole side is inserted, The insertion hole is formed with a female thread into which the male thread of the adapter screws, The portion where the male screw and the female screw screw together has a seal structure. Mounting structure for fuel injection valve.

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