JPS5853235B2 - Mounting structure of hose and hose cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mounting structure for a hose and a hose cap, which has a high sealing property between a metal insert and a rubber hose inserted into the outer surface of the metal insert, and in which the rubber hose is less likely to separate from the metal insert.

Conventionally, in order to maintain the seal between the insert fitting and the rubber hose inserted into the outer surface of the insert fitting and to prevent the insert fitting from being pulled out in the longitudinal direction, adhesive methods were used in which an adhesive was applied between the insert fitting and the rubber hose, or Various types of unevenness are provided on the surface of the metal insert, and methods such as band tightening or caulking are used for tightening.

However, the adhesive method requires complete adhesion between the insert metal fitting and the rubber hose inserted into the outer surface of the insert metal fitting, and requires many management processes such as cleaning, surface treatment, and primer application. Due to the high cost, most methods are currently used for easy tightening.

However, due to the following reasons, the tightening method cannot completely solve both the problems of sealing performance and separation resistance between the insert fitting and the rubber hose, and the tendency is to ignore the high cost and adopt an adhesive type. There are two steps ahead.

In other words, the material of the inner rubber layer of the rubber hose inserted into the outer surface of the insert fitting is regulated (mostly nitrile butadiene rubber) in order to resist the fluid flowing inside the rubber hose, and the inner rubber layer has a hard JIS hardness. (approximately 65 to 75 degrees), the inner circumferential surface of the inner rubber layer and the surface of the insert metal fitting do not fit together. Also, due to the allowable stress of the rubber material, tightening is not limited by pressure. One reason is that high sealing performance cannot be obtained, and another reason is that the compressive force that was initially lost in the rubber hose cannot be maintained due to heat aging fatigue, and the above problem occurs with long-term use. be.

This invention was devised in view of the above problems, and the object is to provide a connection structure between a hose and a hose cap that can be expected to have the same effect as the adhesive method even if it uses a tightening method without using an adhesive method. One of the purposes is to provide a mounting structure for the hose and hose cap that has high airtightness between the insert fitting surface and the inner rubber layer of the rubber hose and reduces oil leakage. To provide a mounting structure for a hose and a hose cap, in which the end of a rubber hose inserted into the outer surface of a metal fitting is less likely to come off from the insert metal fitting.

In order to achieve the above object, the present invention provides a hose mounting structure that includes: an outer fitting surrounding the end of the hose, an insert fitting into which the hose end is inserted, and an inner rubber layer of the rubber hose inserted into the outer peripheral surface of the insert fitting. A sheet of fluorine rubber, which is softer than the inner rubber layer, is disposed between the rubber hose and the inner rubber layer, and the outer metal fitting applies compression to the rubber hose and the fluorine rubber sheet from the outer circumferential surface of the rubber hose in the radial direction to fix the rubber hose and the fluorine rubber sheet.

It is not necessary to use specially formulated fluororubber as the fluororubber placed between the insert fitting and the rubber hose, but if hard fluororubber is used, it will be difficult to adhere to the unevenness due to the insert fitting's rough surface, leading to oil leakage. Therefore, use fluorine rubber as soft as possible (JIS hardness 70° or less)
It is preferable to use a sheet-like material with a thickness of 0.05 nm to 1 mm.

Also, the reason why we chose to use fluorine rubber is that other rubbers not only have low frictional resistance between the rubber sheet and the insert fitting when compressed, but also silicone rubber, which has the same heat resistance as fluorine rubber. This is because the frictional resistance after heat aging is lower than that of the blank, and the object of the present invention cannot be achieved.

For example, according to an experiment by the inventor of this invention, two rubber sheets with a JIS hardness of 70° and a size of 20 mrn x 20 mm x 2 were made from nitrile butadiene rubber used as the inner rubber layer of a comb hose. The rubber sheet was kept under 20% compression on both sides of a brass metal plate that was wider than the width of the rubber sheet, and the force required to pull out the metal plate after 24 hours at room temperature was measured, and the force was approximately 50 kg. Ta.

In addition, in the heat aging test, the pulling force after 160 hours at 120° C. was measured, and the force was 29 kg.

On the other hand, when fluororubber with a JIS hardness of 700 was used in the same test method, the pulling force after 24 hours at room temperature was 550 kg, and the pulling force after 160 hours at 120°C was 800 kg. It has been found that the adhesion is about 10 times higher than that of rubber, and even 20 times higher after heat aging.

The figure shows how the fluoro rubber sheet according to the present invention is used. Fig. 1 shows a cylindrical insert fitting 10 with no irregularities on the surface, and a fluoro rubber sheet 2 with a thickness of about 0.5 mm on the metal surface.
After winding without gluing, fit and press the end of the rubber hose 3 on the outer surface, caulk the outer metal fitting 4 against the insert metal fitting 1 from the outer surface of the rubber hose 3, and compress the end of the rubber hose 3 and the fluoro rubber sheet 2. The example given is illustrative.

Further, FIG. 2 shows an example in which the fluororubber sheet 2 is wound only at the caulked position without being partially bonded in the manner of use shown in FIG. 1.

Further, FIG. 3 shows a usage mode when the insert metal fitting 1 is formed with unevenness 1a.

The fluororubber sheet 2 may be used by forming a sheet in advance and winding it, or by applying rubber paste-like rubber to the surface of the insert fitting to a certain thickness and drying it. You can insert and use either one.

In addition, a shrink tube may be used to ensure good contact with the surface of the insert.

Examples will be described below.

The cap used in the test was made of brass.

The insert fitting was a cylindrical body with an inner diameter of 6 mm and an outer diameter of 8 holes, and the fitting length with the rubber hose was 2 cm.

A cylindrical body with an outer diameter of 16 mm and an inner diameter of 14 mm was used as the outer metal fitting.

The rubber hose has an inner diameter of 7 mm and an outer diameter of 13.8 mm, and has a braided reinforcing layer of vinylon thread in the middle, and the inner rubber layer has a JIS hardness of 70.
0 nitrile butadiene rubber was used.

As the fluororubber disposed between the metal insert and the inner rubber layer, a sheet having a JIS hardness of 60° and a thickness of 0.1 mm was wound around the surface of the metal insert to a width of 18 mm without overlapping.

Then, with a sheet of fluorine rubber wrapped around the surface of the insert fitting, a rubber hose is fitted to the outer circumference of the insert fitting so as to overlap by a length of 2 cm, and the outer fitting fitted to the outer circumference is attached to the insert fitting in a known manner. Tighten by 18% in diameter at two locations using the caulking method,
The cap and rubber hose were combined.

Next, place the joint of the rubber hose in water, close one end of the insert fitting, send nitrogen gas into the rubber hose, and measure the gas pressure when air bubbles form in the water near the fitting to ensure an airtight seal between the fitting and the rubber hose. When I checked the gender, it was as follows.

On the other hand, the case where the fluororubber rubber sheet of the present invention was not used was as follows.

Further, when a rubber sheet of nitrile butadiene rubber was used instead of the fluororubber of the present invention, the results were as follows.

In addition, the pull-out force of the insert fitting and rubber hose was measured, and the results were as follows.

When the fluororubber rubber sheet of this invention is used When the fluororubber rubber sheet of this invention is not used When a rubber sheet of nido-1-lurevbutadiene rubber is used instead of the fluororubber of this invention The hose of this invention As mentioned above, the mounting structure of the hose fitting is such that a rubber sheet that is softer than the inner rubber layer is interposed between the insert fitting and the inner rubber layer of the rubber hose, and the outer fitting radially connects the rubber hose to the rubber hose and the fluoro rubber sheet from the outer periphery. Since compression is applied, the adhesion between the soft rubber sheet and the inner rubber layer is obviously high, and the adhesion to the surface of the insert fitting is high, improving the sealing between the insert fitting and the inner rubber layer. be able to.

In addition, since fluorine rubber is used for the soft rubber sheet, fluorine rubber has a large frictional resistance with metal, so it does not slide on the metal surface, and when compressed, it sticks out laterally from the initial placement area. Since there is less slippage on the metal surface, the initial compressive stress can be maintained, and the above effect and the assembly type can maintain high sealing performance and separation resistance between the insert metal fitting and the inner rubber layer.

In addition, since fluororubber is used for the soft rubber sheet, the fluororubber has high adhesion to metal after undergoing heat aging under compression, so the above effect and the molding structure make the insert suitable for long-term use. High sealing performance and separation resistance between the metal fittings and the inner rubber layer can be maintained.

Furthermore, since fluororubber is used for the soft rubber sheet, fluororubber has a high coefficient of friction with metal, so you can easily tighten it without applying adhesive and expect the same effect as the adhesive method. The tightening pressure can be reduced and the structure of tightening can be simplified.

[Brief explanation of the drawing]

1 to 3 are partial side sectional views showing how the mounting structure for a hose and a hose cap according to the present invention is used. 1...Insert fitting, 2...Fluororubber sheet, 3...Rubber hose, 4...
・Outer metal fittings.

Claims (1)

[Claims] 1. In the hose mounting structure, an outer fitting surrounding the hose end, an insert fitting into which the hose end is inserted,
A sheet of fluororubber, which is softer than the inner rubber layer, is placed between the outer circumferential surface of the insert fitting and the inner rubber layer of the rubber hose to be inserted, and the outer fitting is arranged in a radial direction so that the outer circumferential surface of the rubber hose is closer to the rubber hose and the fluororubber. A mounting structure for a hose and a hose fitting, characterized in that the sheet is compressed and fixed.