JP2003232447A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device 1 capable of restricting problems of permeation of fuel, and thus achieving excellent sealing performance, in a sealing device 1 used in an automotive fuel injector 2. <P>SOLUTION: This sealing device 1 used in the automotive fuel injector 2 is provided with an O-ring 5 of fluororubber, where the minimum crush rate when the O-ring 5 is assembled is set as 15% or more. The sealing device 1 used in the automotive fuel injector 2 is provided with the O-ring 5 of fluororubber, where the minimum crush rate when the O-ring 5 is assembled is set as 20% or more, with the maximum crush rate set as less than 30%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device,
More specifically, the present invention relates to a sealing device that is used in a fuel injector for an automobile and that includes an O-ring.

[0002]

2. Description of the Related Art In a sealing device for sealing between two members using an O-ring made of a rubber-like elastic material, the O-ring is used in a compressed state in order to eliminate a gap with a mating member.
In consideration of the dimensional tolerances of the O-ring and the mating surface, the minimum crushing rate of the O-ring is 8-12% to fill the gap, and there is no problem with the sealing property.

However, in the case of sealing gasoline or light oil in a fuel injector for automobiles or the like, the phenomenon that the fuel permeates the O-ring occurs, and therefore the sealing performance cannot be ensured simply by filling the gap. There is concern that fuel permeation may adversely affect the environment, and in particular there are regulations on the emission of hydrocarbons, which are harmful substances in foreign countries.Therefore, it is required to suppress the fuel permeation of the sealing device used for automobile fuel injectors as much as possible. Has been. It should be noted that here, for fuel permeation, both a very small gap leak that flows out from a gap between an O-ring attachment member such as an injector part and a housing part and the O-ring, and a permeation leak that permeates the inside of the O-ring. included. The minimum crushing rate means the O-ring crushing rate when the dimensional tolerance of the O-ring mounting member is maximum and the dimensional tolerance of the O-ring wire diameter is minimum.

[0004]

In view of the above points, the present invention is capable of suppressing the problem of fuel permeation in a sealing device used for a fuel injector for automobiles and thus exhibiting excellent sealing performance. The object is to provide a possible sealing device.

[0005]

In order to achieve the above object, a sealing device according to claim 1 of the present invention is a sealing device used in a fuel injector for an automobile, comprising a fluorine rubber O-ring, The feature is that the minimum crushing rate when the O-ring is assembled is set to 15% or more.

Further, a sealing device according to claim 2 of the present invention is a sealing device used for a fuel injector for an automobile, comprising an O-ring made of fluororubber, and having a minimum crushing rate of 20 when the O-ring is assembled. %, And the maximum crushing rate is set to less than 30%.

In the inventions according to both of the above claims, the minimum crushing rate is the O-ring crushing rate when the dimensional tolerance of the O-ring mounting member is the maximum and the dimensional tolerance of the O-ring wire diameter is the minimum, as described above. Say that. On the contrary, the maximum crushing rate is the O-ring crushing rate when the dimensional tolerance of the O-ring mounting member is minimum and the dimensional tolerance of the O-ring wire diameter is maximum.

The O-ring made of fluororubber is characterized in that it is excellent in fuel impermeability due to the characteristics of its material. Further, according to the sealing device according to claim 1 of the present invention having the above-mentioned structure, the O-ring is Since the minimum crushing rate at the time of assembling is set to a relatively high range of 15% or more, the fuel permeation amount can be significantly reduced as compared with the conventional case.

Further, according to the sealing device of the second aspect of the present invention, the fuel permeation amount is substantially set in order to set the minimum crushing rate when the O-ring is incorporated to 20% or more and the maximum crushing rate to less than 30%. It is possible to suppress it to near zero, and within this range, it is possible to suppress the occurrence of compression cracks in the O-ring due to excessive compression.

As a method of changing the crushing rate of the O-ring, the wire diameter or thickness of the O-ring is changed, or the dimensions of the O-ring mounting member (bottom diameter dimension of the mounting groove or inner diameter dimension of the housing) are changed. Methods and the like.

The sealing device of the present invention is used, for example, at a connecting portion between a delivery valve and an injector used when fuel is supplied from a fuel tank to the injector.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a sealing device 1 according to an embodiment of the present invention.
2 is a cross section of the fuel injector 2 for an automobile, in which an O-ring 5 mounted on an annular mounting groove 4 provided on the peripheral surface of the injector part 3 is provided on the inner peripheral surface of the pipe part 6 of the delivery part. The close contact is configured to seal the fuel (not shown) as the sealing fluid.

The O-ring 5 is made of fluororubber and has a minimum crushing rate of 15% or more when assembled.
For example, it is set to 20%. The cross section of the O-ring 5 is circular or substantially circular. Also this O-ring 5
A silicon coating (not shown) may be applied to the surface of the product if necessary.

As shown in FIG. 2, the crushing rate k of the O-ring 5 is k = (ab) / a × 100 ... Where a is the wire diameter before compression and b is the wire diameter after compression. It is represented by the formula (1), and the minimum crushing rate is as described above, the O-ring mounting member (in the embodiment, the injector part 3
And the delivery pipe part 6) has the maximum dimensional tolerance and O
The crushing rate of the O-ring 5 when the dimensional tolerance of the wire diameter of the ring 5 is minimum.

Therefore, as described above, the fluorine rubber O
When the minimum crushing rate when the ring 5 is assembled is set to a value higher than the conventional one, for example, 20%, the fuel that is the sealing fluid becomes O.
It becomes difficult to pass between the ring attachment member and the O-ring 5, and it becomes difficult to permeate the inside of the O-ring 5, so that the fuel permeation amount can be reduced.

When an experiment was conducted using an O-ring 5 made of fluororubber having an inner diameter of 7.5 mm and a wire diameter of 3.5 mm, the following results were obtained.

That is, when the O-ring 5 is attached to a predetermined position of the experimental equipment and the crushing rate is gradually increased, the fuel permeation amount gradually decreases as shown in the graph of FIG.
The fuel permeation rate at a crushing rate of 15% is about 12 mg / da
y, which is the maximum value of the conventional crushing rate 12
The fuel permeation amount in% is about 23 mg / day, while the reduction is about 50%. When the crushing rate exceeds 20%, the fuel permeation amount is approximately 3 mg / day or less, which is a state approaching zero. Therefore, by setting the crushing rate when the O-ring is installed to 15%, the fuel permeation amount can be reduced to about half of the conventional amount, and by setting it to 20% or more, the fuel permeation amount approaches zero. I was able to confirm that it can be reduced until.

Further, since cracking of the O-ring 5 due to compression occurs when the crushing rate is 30% or more, setting the crushing rate to less than 30% causes compression cracking of the O-ring 5. Can be suppressed.

Further, since a silicon coating is formed on the surface of the O-ring 5 as well, the low frictional property of silicon is utilized to reduce the increase of the insertion load due to the increase of the crushing rate. be able to.
As a material of the surface coating for reducing the increase of the insertion load of the O-ring 5, Teflon (registered trademark) can be used in addition to silicon, but silicon is preferable from the viewpoint of durability.

[0021]

The present invention has the following effects.

That is, first, in the sealing device according to claim 1 of the present invention having the above structure, since the O-ring is made of fluororubber, it is possible to exhibit excellent fuel impermeability. Since the minimum crushing rate when the ring is assembled is set to a relatively high value of 15% or more, the fuel permeation amount can be markedly reduced as compared with the conventional case, and the sealing performance can be improved.

A second aspect of the present invention having the above structure.
Since the O-ring is made of fluororubber, it is possible to exhibit excellent fuel impermeability in the sealing device according to 1. Also, the minimum crushing rate when incorporating the O-ring is 20
% Or more, and set the maximum crushing rate to less than 30%,
The amount of fuel permeation can be suppressed to near zero and the sealing performance can be improved. Further, it is possible to suppress the occurrence of compression cracks in the O-ring due to excessive compression.

According to the present invention, the O-ring having the above-mentioned structure is applied to a fuel injector for an automobile, which is important for the problem of fuel permeation and has to be a fluororubber O-ring because of the problems of chemical resistance and fuel resistance. It has particular significance in its use.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a fuel injector for a vehicle using a sealing device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the sealing device.

FIG. 3 is a graph showing a relationship between a crushing rate and a fuel permeation amount.

[Explanation of symbols]

1 Sealing device 2 Automotive fuel injectors 3 injector parts 4 mounting groove 5 O-ring 6 Delivery pipe part

Claims (2)

[Claims] 1. A sealing device (1) used for a fuel injector (2) for an automobile, comprising an O-ring (5) made of fluororubber, and having a minimum crushing rate when the O-ring (5) is assembled. A sealing device characterized by being set to 15% or more. 2. A sealing device (1) used for a fuel injector (2) for an automobile, comprising an O-ring (5) made of fluororubber, and having a minimum crushing rate when the O-ring (5) is assembled. 20% or more,
A sealing device having a maximum crushing rate of less than 30%.