JPH06221472A - Hose for automobile fuel piping - Google Patents

Abstract

PURPOSE:To provide a low-cost hose for automobile fuel piping excellent in all of gasoline permeation resistivity flexibility, kink resistivity, fitting workability and sealing. CONSTITUTION:A hose 1 for automobile fuel piping comprises an inner layer 2 and an outer layer 3 formed outside the inner layer 2. The inner layer 2 is formed by polyamide resin containing a plasticizer and the outer layer 3 is formed by a rubber elastic material. And then, thickness of the inner layer 2 is relatively set at 1/30 or more of the inside diameter of the hose which is assumed to be 1, and thickness of the outer layer 3 is relatively set at 1/6 or more of the inside diameter of the hose which is assumed to be 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle fuel pipe hose used as a low pressure hose such as an evaporative hose, a breather hose and a fuel hose for connecting an automobile gasoline tank and an engine.

[0002]

[Field of Industrial Application] Fuel lines for automobiles are generally composed of metal pipes and hoses for connecting these metal pipes. Examples of such hoses include an evaporative hose connecting a gasoline tank to an engine, a breather hose used for an air bleeding portion of a gasoline tank, and a low pressure fuel hose connecting an engine to a gasoline tank. The hose is
For example, an inner tube rubber layer made of acrylonitrile-butadiene rubber (NBR), a reinforcing thread layer made of braid knitting or spiral knitting of polyester threads on the outer circumference of the inner tube rubber layer, and a rubber elastic material on the outer circumference of the reinforcing thread layer. And an outer tube rubber layer. In the case of a low pressure fuel hose, chloroprene rubber (CR), epichlorohydrin rubber (CHC), chlorosulfonated polyethylene rubber (CSM) or the like is used as the rubber elastic material. As the evaporative hose and the breather hose, a mixture of CR, CHC, CSM, NBR and polyvinyl chloride (PVC) is used.

With respect to these hoses, a phenomenon occurs in which vaporized gasoline permeates the hoses and leaks to the outside. In recent years, in particular, the number of automobiles has been increasing, and environmental deterioration due to gasoline leaking from such hoses has become a serious problem. Therefore, it has been enacted to regulate the amount of vaporized gasoline that leaks from such automobiles. Especially, since 1994, in California, the United States, the permeation amount of unburned evaporated gasoline from evaporative hoses is strictly regulated. Therefore, it is regulated to about 1/10 or less of the conventional gasoline permeation amount. Further, since the fuel consumption standard line has been regulated more severely since 1996, weight reduction is demanded from the viewpoint of improving fuel consumption. For these reasons, a hose has been proposed in which fluororesin (FKM) is used in place of NBR, which is the material for forming the inner tube rubber layer. The hose made of FKM can suppress the permeation amount of vaporized gasoline,
The cost is high because the FKM is expensive. Therefore, an alternative to the FKM having excellent gasoline permeation resistance is being investigated. However, as an alternative to the FKM, even if it has excellent gasoline permeation resistance, its rigidity is so high that it is inferior in flexibility, inferior in kink resistance (buckling resistance), and difficult to insert into a metal pipe. There are various problems that workability is poor and sealability is poor.

The present invention has been made in view of the above circumstances, and is a low-cost automobile fuel pipe hose excellent in gasoline permeation resistance, flexibility, kink resistance, assembling workability and sealing performance. The purpose is to provide.

[0005]

In order to achieve the above object, an automobile fuel pipe hose of the present invention is an automobile fuel pipe hose having an inner layer and an outer layer formed on the outer periphery of the inner layer. The inner layer is formed of a plasticizer-containing polyamide resin, the outer layer is formed of a rubber elastic material, and the thickness of the inner layer is relatively set to 1/30 or more with the inner diameter of the hose being 1 or more. The thickness is relatively set to 1/6 or more with the inner diameter of the hose being 1.

[0006]

That is, the inventors of the present invention have conducted a series of studies in order to obtain a hose for automobile fuel piping, which is excellent not only in gasoline permeation resistance but also in kink resistance, assembling workability and flexibility. As a result, when an outer layer made of a rubber elastic material is formed on the outer periphery of an inner layer made of a polyamide resin containing a plasticizer, the inner layer made of a polyamide resin has excellent gasoline permeation resistance and the outer layer is made of a rubber elastic material. By using, the kink resistance is improved and the assembling workability is also improved. Further, it has been found that the flexibility of the entire hose is improved by forming the inner layer to have a relatively small thickness with respect to the inner diameter of the hose and the outer layer to have a larger thickness than that of the inner layer. did.

Next, the present invention will be described in detail.

The automobile fuel pipe hose of the present invention comprises an inner layer formed of a plasticizer-containing polyamide resin and an outer layer formed of a rubber elastic material on the outer periphery of the inner layer.

The inner layer is obtained by using a plasticizer-containing polyamide resin. Examples of the polyamide resin include nylon 11, nylon 12, nylon 610 and the like. The plasticizer to be contained is not particularly limited, and conventionally known ones such as n-benzenesulfonic acid amide can be mentioned. The content of the plasticizer is 20% by weight in the polyamide resin (hereinafter referred to as “%”).
It is preferable to set the following ratio. That is, when the content of the plasticizer exceeds 20%, the amount of permeation of fuel oil such as gasoline increases, and the gasoline permeation resistance tends to deteriorate.

The outer layer is formed by using a rubber elastic material. Examples of the rubber elastic material include CR, CSM, a mixture of NBR and PVC, CHC, ethylene-propylene-diene rubber (EPDM), chlorinated polyethylene rubber (CP).
E), acrylic rubber (ACM) and the like.

The automobile fuel piping hose of the present invention is manufactured, for example, as follows. That is, first, a polyamide resin containing a plasticizer is extruded into a tubular shape by an extruder. Next, the outer peripheral surface of the plasticizer-containing polyamide resin tubular body produced by extrusion molding is treated with an adhesive. Then, a rubber elastic material is extruded on the adhesive-treated surface while pressurizing the inner layer with air to form a rubber outer layer. Then, the vehicle fuel pipe hose 1 having a two-layer structure as shown in FIG. 1 is manufactured by performing heat vulcanization at a predetermined temperature. In the figure, 2 is an inner layer made of a plasticizer-containing polyamide resin, and 3 is an outer layer made of a rubber elastic material.

In the thus obtained automobile fuel piping hose, the thickness of each layer is preferably set to a relative value of 1/30 or more when the inner diameter of the hose is 1. The thickness of the outer layer 3 is preferably set to 1/6 or more. Specifically, when the inner diameter of the hose is 3.0 to 15.0 mm, the thickness of the inner layer 2 is 0.1 to 0.1 mm.
It is preferable to set it in the range of 1.0 mm, and it is preferable to set the thickness of the outer layer 3 in the range of 2.0 to 4.0 mm. Particularly preferably, the inner layer 2 has a thickness of 0.3 to 0.5.
mm, and the thickness of the outer layer 3 is 2.7 to 2.9 mm.

Further, the ho for automobile fuel piping of the present invention
Inner layer 2 made of a plasticizer-containing polyamide resin
Flexural modulus of 2000-15000 kgf / cm²of
It is preferable to set the range. Particularly preferably 300
0 to 10000 kgf / cm ²Is. Also rubber elasticity
The hardness of the outer layer 3 made of material is set to 45 to 75 (Hs).
Is preferable, and particularly preferably 55 to 70 (Hs)
Is. By setting the characteristics of each layer as described above,
Kink, flexibility, airtightness, workability in assembly (to metal pipes
So that a hose with excellent
It

The two-layer structure automotive fuel pipe hose 1 having the inner layer 2 and the outer layer 3 thus formed is used by being inserted into a metal pipe 4 as shown in FIG. 2, for example.

[0015]

As described above, the automotive fuel pipe hose of the present invention has a two-layer structure in which the outer layer is formed of the rubber elastic material on the outer peripheral surface of the inner layer formed of the plasticizer-containing polyamide resin. is there. Moreover, the thickness of the inner layer and the thickness of the outer layer are set to predetermined values with reference to the inner diameter of the hose. Therefore, the thickness of the inner layer is set to be small, and it has excellent gasoline permeation resistance and is highly flexible, and is also excellent in kink resistance, airtightness, assembling workability, and pressure resistance. Therefore, the vehicle fuel piping hose of the present invention is most suitable for a low pressure hose such as an evaporative hose, a breather hose and a fuel hose for connecting a gasoline tank of a vehicle and an engine.

Next, examples will be described together with comparative examples.

[0017]

Examples 1 to 8 and Comparative Examples 1 to 3 Using the raw materials shown in the following Tables 1 to 3, hoses for automobile fuel pipes were obtained according to the above production method. The thickness and flexural modulus of the inner layer, the thickness and hardness of the outer layer, and the inner diameter of the hose are also shown in Tables 1 to 3 below. The vulcanization conditions are 150 ° C. and 35
Set to minutes. The bending elastic modulus of the inner layer was measured as follows. That is, based on the three-point bending test method in the plastic bending test method, a predetermined size (length: 80 ± 5 mm, width: 10 ± 0.5 mm, thickness:
4 ± 0.2 mm) was formed into a test piece. Then, using the device shown in FIG. 3, the test piece 7 is laid over the two support bases 6,
From the center, press the wedge 5 at a constant speed (30 mm / mi
It was lowered in n). The load-deflection curve at this time was recorded on a chart paper, and the bending elastic modulus was calculated by the following formula.

E = L ³ / (4 × bh ³ ) × F / Y E: Flexural modulus (kgf / cm ² ) L: Distance between fulcrums b: Width of test piece (cm) h: Test piece Thickness (cm) F: load-load at a point arbitrarily selected on the first straight line portion of the deflection curve (kgf) Y: amount of deflection at load F (cm)

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

Comparative Example 4 A hose for automobile fuel piping having a single-layer structure made of a polyamide resin containing a plasticizer was produced.

[0023]

COMPARATIVE EXAMPLE 5 An inner layer tubular body was extruded using NBR,
Then, a reinforcing yarn layer was formed on the outer periphery of the inner layer tubular body by braiding a polyester yarn. Then, the outer layer was extrusion-molded on the outer periphery of the reinforcing yarn layer by using CR. Thus, a hose for automobile fuel piping was manufactured.

The gasoline permeation resistance, kink resistance, flexibility, airtightness, assembling workability, and pressure resistance of each automobile fuel piping hose obtained as described above were measured and evaluated. Further, the flexural modulus of the inner layer of the automobile fuel piping hose which is an example product was measured. Then, from the above measurement results, each hose was comprehensively evaluated in three stages. That is, ◯ is excellent, Δ is normal, and X is poor. The results are shown in Tables 4 to 6 below. The evaluation of each of the above characteristics was performed according to the following methods.

[Gasoline permeation resistance] As shown in FIG.
A sample (hose) 10 cut into a specified length (free length of 500 mm) is provided with two pipes 13 and 1 of a fuel tank 12.
It was fitted in the No. 4 and fixed by the clamp 15. Next, the fuel tank 12 was filled with the sample fuel (specified gasoline) 11 to 85% of the tank capacity, and the fuel 11 was brought into contact with the entire surface of the sample 10, and was placed in a 40 ° C. constant temperature bath. 1
It was left for 68 hours. Then, after standing, the sample 10
Was removed from the fuel tank 12, and both ends of the sample 10 were fitted into the two pipes 17 and 18 formed on the upper surface of the fuel tank 16 shown in FIG. Next, the fuel tank 16 was filled with about 100 cc of new specified gasoline 11, and the inside of the sample 10 was made into a gasoline vapor shape. Then, in this state, the total weight was measured every 24 hours in a constant temperature bath at 40 ° C. for 3 days. Then, the gasoline permeation amount was calculated by the following formula.

Θ = [Wn-W (n-1)] / S In the above equation, Θ is the amount of permeation per day (g / m ² / da).
y), S is the area (m ² ) of the outer surface of the sample 500 mm, W
n is the mass (g) of the sample set state after n days, and n is an integer of 0 to 3.

[Kink resistance] As shown in FIG.
A sample (hose) 19 of m was used to make a ring, the crossing portion was held by hand, and the sample 19 was pulled in the direction of the arrow and held for 1 minute. After being held, the outer diameter D ₁ (m
m) was measured to determine the retention rate. Next, the diameter of the ring of the kneaded R portion was calculated by further reducing the diameter of the ring. The retention rate was calculated by the following formula.

Retention rate (%) = (D ₁ / D) × 100 In the above formula, D is the outer diameter (m) of the initial sample (hose).
m). However, both D ₁ and D are samples (hoses)
It is the minor axis of the outer diameter.

[Flexibility] A sample (hose) having a length of 150 mm was prepared and used in the plastic bending test method.
It measured based on the point bending test method. That is, as shown in FIG. 7, two hoses 21 are bridged over the support base 20 and the pressure wedge 22 is moved from the center of the hose 21 to 30 mm / mi.
It was lowered at a speed of n, and the relationship between displacement and weight at this time was measured.

[Airtightness] As shown in FIG.
Both ends of the mm sample (hose) 23 were attached and fixed to the pipe portion 25 of the fixing jig 24. Next, air (or an inert gas) was sent from the direction of the arrow to the hole at the end of the fixing jig 24 to fill the inside of the hose 23 with a prescribed pressure and immerse it in a water tank. Then, after the lapse of the specified time, the presence or absence of leakage of the pressurized gas was examined.

[Assembling workability] As shown in FIG.
A 0 mm sample (hose) 26 was installed upright and a pipe 28 attached to a compression tester 27 was moved at a speed of 3 in the direction of the arrow.
It was inserted into the hose 26 at 0 mm / min. The maximum load during the insertion was measured.

[Pressure resistance] A hose having a length of 300 mm was attached to a burst tester, and a sample (hose) was filled with a pressurized liquid (water or oil). Then, 70kgf / min
The pressure at the time of bursting was measured by pressurizing at a pressurizing rate of cm ² .

[0033]

[Table 4]

[0034]

[Table 5]

[0035]

[Table 6]

From the results of Tables 4 to 6 above, the products of Examples are
It can be seen that while it has excellent gasoline permeation resistance, it also has excellent kink resistance, flexibility, airtightness, assembly workability, and pressure resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view showing an example of the configuration of an automobile fuel piping hose of the present invention.

FIG. 2 is a sectional explanatory view showing a usage state of the automobile fuel piping hose of the present invention.

FIG. 3 is an explanatory diagram showing a method for measuring a bending elastic modulus of a hose.

FIG. 4 is an explanatory diagram showing a method of measuring and evaluating gasoline permeation resistance of an automobile fuel piping hose.

FIG. 5 is an explanatory diagram showing a method for measuring and evaluating gasoline permeation resistance of an automobile fuel piping hose.

FIG. 6 is an explanatory diagram showing a method for measuring and evaluating kink resistance of an automobile fuel piping hose.

FIG. 7 is an explanatory diagram showing a method for measuring and evaluating the flexibility of a hose for automobile fuel piping.

FIG. 8 is an explanatory diagram showing a method for measuring and evaluating the airtightness of an automobile fuel piping hose.

FIG. 9 is an explanatory diagram showing a method of measuring and evaluating the workability of assembling an automobile fuel piping hose.

[Explanation of symbols]

 1 Automotive fuel piping hose 2 Inner layer 3 Outer layer

Claims (1)

[Claims] 1. A hose for automobile fuel piping, comprising an inner layer and an outer layer formed on the outer periphery of the inner layer, wherein the inner layer is formed of a plasticizer-containing polyamide resin and the outer layer is formed of a rubber elastic material. And the thickness of the inner layer is relatively set to 1/30 or more with the inner diameter of the hose being 1 and the thickness of the outer layer is 1/30 with the inner diameter of the hose being 1.
A hose for automobile fuel piping, which is relatively set to 6 or more.