JP4709403B2 - Bolt joint seal structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bolt joint sealing structure that prevents internal fluid from leaking out from a bolt fastening portion in a bolt fastening portion that is fastened through an inside and outside containing fluid such as a casing of a device.
[0002]
[Prior art]
In a bolt fastening portion that is fastened through inside and outside containing fluid such as a casing of a device, there is a problem that fluid leaks through a gap between the fastening hole and the fastening bolt.
[0003]
As shown in FIG. 2, for example, a main bearing base side bolt (hereinafter simply referred to as “bolt”) 01 of a main bearing base of a diesel engine body is fastened sideways with the main bearing base. It is necessary to prevent leakage between the bolt hole 2 and the bolt 01.
[0004]
That is, when fastening is performed by screwing the nut 03 into the threaded portion 01a at the tip of the bolt 01 inserted into the bolt hole 2 of the material to be fastened 4, the surface 4a around the bolt hole opening of the material to be fastened 4 is fastened. The lubricating oil a may leak in the bolt radial direction from the point (A portion in the figure) and from the thread surface (B part in the drawing) between the bolt 01 and the nut 03 in the bolt axial direction.
[0005]
Therefore, conventionally, in order to prevent leakage of the lubricating oil a from the portion A, an annular groove surrounding the bolt 01 is provided on the surface in contact with the surface 4a around the bolt hole opening of the nut 03, and the O-ring 05 is attached. A cap 06 having a closed end in a bag shape is screwed and attached to the foremost portion protruding from the nut 03 of the screw portion 01a of the bolt 01, and an annular groove surrounding the bolt 01 is provided on the cap side surface of the nut 03 to provide an O-ring. 07, the cap 06 was brought into close contact with the nut 03, and leakage from between the nut 03 and the cap 06 was eliminated, thereby preventing leakage of the lubricating oil a from the B portion.
[0006]
[Problems to be solved by the invention]
However, in the conventional bolt joint sealing structure shown in FIG. 2 described above, it is necessary to process a special nut 03 having an O-ring annular groove on both sides, and the O-ring 05 is broken when the nut 03 is fastened. In addition, there is a problem that the O-ring 07 is broken when the cap 06 is attached, and there is a problem that, in addition to the nut 03, a part that is not for direct fastening such as the cap 06 is required.
[0007]
The present invention eliminates the problems of the conventional bolt joint seal structure and provides a bolt joint seal structure capable of preventing fluid from leaking through the bolt with only the fastening components. It is to be an issue.
[0008]
[Means for Solving the Problems]
(1) The present invention has been made in order to solve the above-described problems, and as a means thereof, a nut is screwed into a screw portion at a tip portion of a bolt protruding from a bolt hole of a material to be fastened, and is fastened. In the bolt joint sealing structure, the bolt is slightly smaller in diameter than the diameter of the bolt hole before and after the opening of the bolt hole, and has a large-diameter stem portion having a smooth peripheral surface, A washer having a through hole having a diameter slightly larger than the large-diameter stem portion is inserted between the material and the nut, and a chamfered surface is formed at the corner of the end of the through-hole of the washer on the fastened material side. An annular space surrounding the bolt between the surface around the opening of the bolt hole of the material to be fastened, the smooth peripheral surface of the large-diameter stem portion, and the chamfered surface in a state where the nut is fastened. And a circular cross section in the annular gap. One O-ring is pressure-fitted to seal between the O-ring and the surface around the opening of the bolt hole of the material to be fastened, and between the O-ring and the smooth peripheral surface of the large-diameter stem portion. The bolt is provided with a portion having a diameter smaller than that of the screw portion on the bolt hole side of the screw portion, and the large-diameter stem portion is a part of a portion having a diameter smaller than that of the screw portion. And a part of the large-diameter stem portion is inserted into the bolt hole, and the diameter of the smooth peripheral surface of the large-diameter stem portion is larger than the diameter of the screw portion. Provided is a sealing structure for a bolt joint. Preferred means, the surrounding surface of the opening of the bolt hole before Symbol fastened member provides a sealing structure for bolted connection, characterized in that it is smooth finish. Further, as a preferable means, the annular gap is formed in a state where the nut is fastened, a surface around a bolt hole opening of the material to be fastened, the smooth peripheral surface of the large-diameter stem portion, and the chamfer. Provided is a bolt joint sealing structure characterized in that the bolt is surrounded by an isosceles triangle cross section with a surface. Further, as a preferable means, there is provided a seal structure of a bolted joint, wherein an O-ring having a circular cross section is pressed into the annular gap and pressed.
[0009]
According to the configuration of the above means, the O-ring can be prevented from being broken just by being pressed by the washer, and the nut does not need to be provided with an annular groove for the O-ring, and a cap for preventing leakage of the lubricating oil. In the fastening process, the sealing in the two directions of the bolt radial direction and the bolt shaft direction is simultaneously performed at the time of fastening the nut.
[0010]
(2) Moreover, as a preferable means, in the above-described bolt joint seal structure, the bolt is a main bearing base side bolt of a main bearing base of a diesel engine. To do. Moreover, as a preferable means, a seal structure for a bolt joint portion is provided, in which the main bearing stand side bolts are formed laterally at the lower part of the engine.
[0011]
According to a preferred means, in addition to the function of the upper Kite stage, it had to be especially in a diesel engine, a main bearing pedestal of the main bearing pad side bolt carried sideways bolting requiring its structural strength engine lower However, the sealing in that case is facilitated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Based on FIG. 1, the seal structure of the bolt junction part concerning one Embodiment of this invention is demonstrated. Fig.1 (a) is sectional drawing of the bolt fastening part which shows the principal part of this Embodiment, (b) is C section expansion explanatory drawing in (a).
[0013]
In the present embodiment, as shown in FIG. 1, the bolt 1 protruding from the bolt hole 2 of the material to be fastened 4 has a diameter of the bolt hole 2 at a portion located before and after the opening of the bolt hole 2 of the material to be fastened 4. A large-diameter stem portion 1b having a smooth peripheral surface having a slightly smaller diameter is provided, and a screw portion 1a is provided on the tip side of the large-diameter stem portion 1b.
[0014]
A washer 8 having a through hole 8a having an inner diameter slightly larger than the outer diameter of the large diameter stem portion 1b is inserted around the large diameter stem portion 1b, and the nut 3 screwed into the screw portion 1a is covered with the washer 8 interposed therebetween. Fastening material 4 is fastened. The surface 4a around the bolt hole opening of the material to be fastened 4 is smoothed.
[0015]
The washer 8 has a chamfered surface 8b that is chamfered with an angle of an end portion of the through hole 8a on the material to be fastened 4 side of about 45 °. An annular gap 9 is formed surrounding the bolt 1 having an isosceles triangle section surrounded by the peripheral surface 1b, the chamfered surface 8b of the washer 8 and the surface 4a around the bolt hole opening of the material 4 to be fastened.
[0016]
Therefore, in bolt fastening, the O-ring 10 having an appropriate cross-sectional dimension that matches the cross-sectional size of the gap 9 is mounted in the annular gap 9 in advance and then bolted.
[0017]
Then, as shown in FIG. 1B, before the normal fastening, the O-ring 10 having a circular cross section is deformed and pushed into the gap 9 having an isosceles triangular cross section, and in particular, the bolt hole opening of the material to be fastened 4 is opened. The peripheral surface of the large-diameter stem portion 1b and the point E are simultaneously pressed at the point D with the surface 4a around the part.
[0018]
For this reason, at the same time, the O-ring 10 and the surface 4a around the bolt hole opening of the material to be fastened 4 are sealed by the pressure contact at the point D, and the lubricating oil in the bolt radial direction passes between the fastened member 4 and the washer 8. A is prevented from leaking out, and the space between the O-ring 10 and the peripheral surface of the large-diameter stem portion 1b is sealed by the pressure contact at point E, and the peripheral surface of the large-diameter stem portion 1b of the bolt 1 and the surface of the through hole 8a of the washer 3 Leakage of the lubricating oil a in the bolt axial direction passing between the two is prevented.
[0019]
As described above, according to the seal structure of the bolt joint portion of the present embodiment, the O-ring 10 is only pressed by the washer 3 and is not subjected to the shearing force around the bolt shaft, so that conventional breakage is prevented. In addition, the nut 3 does not need to be provided with an annular groove for the O-ring, so that a normal nut can be used, and a cap for preventing leakage of the lubricating oil is not necessary, and parts can be simplified and reduced. In the fastening process, since the sealing in the two directions of the bolt radial direction and the bolt shaft direction is simultaneously performed at the time of fastening the nut, the O-ring mounting fastening is changed from two processes to one process, and the man-hour can be reduced.
[0020]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention. .
[0021]
For example, both the conventional example and the embodiment have been described by taking the main bearing stand side bolts of the main bearing stand of the diesel engine main body as an example, but widely applied to the sealing structure of the bolt joint portion in the airframe, casing, etc. containing fluid inside. It can be done.
[0022]
Of course, especially in a diesel engine, the main bearing stand side bolts of the main bearing stand must be bolted in the lateral direction at the lower part of the engine, which requires strength in terms of structure, and no other preferable bolt fastening seal structure can be found. The problem is solved and the sealing of the main bearing stand side bolts is facilitated, and the effect contributes to the improvement of the diesel engine.
[0023]
【The invention's effect】
(1) a sealing structure of a bolt joint, the sealing structure of the bolted connection for fastening screwed a nut to the threads of the distal end portion of the bolt protruding from the bolt hole of the fastening member, the bolt is a bolt A large-diameter stem portion having a diameter slightly smaller than the diameter of the bolt hole is provided before and after the opening of the hole, and a through-hole having a diameter slightly larger than that of the large-diameter stem portion is provided between the material to be fastened and the nut. A face around the opening of the bolted hole of the material to be fastened in a state where a chamfered surface is formed at a corner of the end of the material to be fastened of the through hole of the washer and the nut is fastened. An annular space surrounding the bolt is formed between the peripheral surface of the large-diameter stem portion and the chamfered surface, and an O-ring is press-fitted in the annular space so that the O-ring and the material to be fastened The space around the opening of the bolt hole is sealed. Since the O-ring and the peripheral surface of the large-diameter stem portion are sealed, the O-ring can be prevented from being broken just by being pressed by a washer. There is no need to provide an annular groove to prevent the lubricant from leaking, and the parts can be simplified and reduced. The fastening process can be performed in two directions, the radial direction of the bolt and the axial direction of the bolt. Since the sealing is performed at the same time, the man-hour can be reduced.
[0024]
(2) In the seal structure, since the bolt is configured to be a main bearing pedestal of the main bearing pad side bolts of the diesel engine, in addition to the upper climate fruit, especially in a diesel engine, the main bearing block of the main bearing The bolts on the side of the pedestal have to be tightened side by side at the lower part of the engine, which requires strength in terms of structure. This solves the problem that no other preferred bolt fastening seal structure has been found, It will make it easier and will contribute to the improvement of diesel engines.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a bolt fastening portion seal structure according to an embodiment of the present invention, wherein (a) is a cross-sectional view of the bolt fastening portion showing the main part of the embodiment, and (b) is ( a) Medium C part expansion explanatory drawing.
FIG. 2 is an explanatory view of a conventional bolt fastening part seal structure, and is a cross-sectional view of a bolt fastening part showing the main part thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bolt 1a Screw part 1b Large diameter stem part 2 Bolt hole 3 Nut 4 Fastening material 4a Surface around bolt hole opening 8 Washer 8a Through hole 9 Cavity part 10 O-ring

Claims (6)

In the bolt joint sealing structure in which a nut is screwed and fastened to a threaded portion at the tip of a bolt protruding from a bolt hole of a material to be fastened, the bolt has a diameter larger than that of the bolt hole before and after the opening of the bolt hole. A washer having a small diameter and a large diameter stem portion having a smooth peripheral surface, and a washer having a through hole having a slightly larger diameter than the large diameter stem portion is inserted between the material to be fastened and the nut. A corner of the end of the through hole of the washer on the side of the material to be fastened has a chamfered surface, and in a state where the nut is fastened, a surface around the opening of the bolt hole of the material to be fastened, and An annular space surrounding the bolt is formed between the smooth peripheral surface of the large-diameter stem portion and the chamfered surface, and an O-ring having a circular cross section is press-fitted in the annular space to Between the surface around the bolt hole opening of the material to be fastened Sealed, are seals between said smooth circumferential surface of the large diameter stem portion and the O-ring,
The bolt includes a portion having a smaller diameter than the screw portion on the bolt hole side of the screw portion,
The large-diameter stem portion is formed in a part of a portion having a smaller diameter than the screw portion, and a part of the large-diameter stem portion is inserted into the bolt hole,
The bolt joint seal structure, wherein a diameter of the smooth peripheral surface of the large-diameter stem portion is larger than a diameter of the screw portion. In the sealing structure of the bolted connection according to claim 1, the surrounding surface of the opening of the bolt hole before Symbol fastened material, the sealing structure of the bolted connection, characterized in that it is smooth finish.   3. The bolt joint seal structure according to claim 1, wherein the annular gap is in a state where the nut is fastened, and a surface around a bolt hole opening of the fastened material and the large-diameter stem portion. A bolt joint sealing structure characterized in that the bolt is surrounded by an isosceles triangle cross section between the smooth circumferential surface and the chamfered surface.   The bolt joint seal structure according to any one of claims 1 to 3, wherein an O-ring having a circular cross section in the annular gap is pressed into the annular gap and is press-fitted. Bolt joint seal structure.   The bolt joint seal structure according to any one of claims 1 to 4, wherein the bolt is a main bearing base side bolt of a main bearing base of a diesel engine.   The main bearing stand side bolt according to claim 5, wherein the main bearing stand side bolt is formed laterally at the lower part of the engine.

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