JPH0718510B2 - Flexible tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention can be applied to a flexible tube, particularly, in a high temperature condition, and can exhibit excellent durability when applied to an application requiring a vibration damping function. It relates to a flexible tube.

(Prior Art) For example, as shown in a schematic diagram in FIG. 3, the vehicle engine e is mounted between a supercharger t and an intercooler i and between the intercooler i and the engine e, respectively. As a conventionally known flexible tube h that functions to prevent engine vibration from being transmitted to the vehicle body as well as to supply engine air supply, there are those illustrated in FIGS.

Here, the flexible tube h shown in FIG. 4 is provided at both ends of a bellows-like portion 1 made of a rubber elastic body, which is located at a central portion in the length direction, and also has smooth tubular portions 2, 2 made of a rubber elastic body. Are continuously formed,
Then, two to three layers of a canvas-like reinforcing layer 3 coated with a rubber elastic body are embedded in the inside of these, and the fifth
The flexible tube h shown in the figure is formed by embedding a cellulose short fiber reinforcing material 5 in a tubular portion 4 made of a rubber elastic body, which is smooth as a whole, in a circumferential direction.

(Problems to be Solved by the Invention) By the way, among the conventional techniques, the flexible tube h shown in FIG. 4 has two to three canvas-like reinforcing layers 3 embedded therein.
There is a problem that the rigidity of the flexible tube itself in the axial direction and the direction orthogonal to that direction is too high and transmission of engine vibration to the vehicle body cannot be effectively prevented, and durability against vibration is low. Further, in this flexible tube h, since the canvas-like reinforcing layer 3 is manually wound and molded, and is further vulcanized by the sheet winding method, the number of molding steps increases,
There has been a problem that the cost of the flexible tube h becomes high and a portion having an uneven thickness is generated during vulcanization, which causes a failure of the flexible tube h during use.

Further, in the flexible tube h shown in FIG. 5, since the short fiber reinforcing material 5 is oriented in the circumferential direction, the durability thereof against repeated displacement in the axial direction and the direction orthogonal to the axial direction is low, There has been a problem that cracks oriented in the orientation direction of the reinforcing material 5 are generated and progress relatively early.

The present invention advantageously solves the above-mentioned problems of the prior art, can be easily and sufficiently homogeneously configured, and can effectively exhibit the vibration damping function under appropriate rigidity, while the internal pressure The invention provides a flexible tube having extremely excellent durability against vibration and the like.

(Means for Solving the Problems) The present invention relates to a flexible tube having an elastic body as a main body and having a bellows-like portion in an intermediate portion thereof, in which a short fiber reinforcing material is embedded without being oriented. Become.

Here, more preferably, the aspect ratio (length / fiber diameter) of the short fiber reinforcing material is set in the range of 200 to 600.

(Operation) In this flexible tube, since the short fiber reinforcing material is uniformly embedded in the elastic body, the strength and rigidity in each direction of the flexible tube are non-oriented. While being effectively improved by the reinforcing body, they are sufficiently uniform over the entire flexible tube, and therefore, when the flexible tube is applied in the same manner as described in the conventional example, the vibration of the engine is transmitted to the vehicle body. The transmission can be effectively prevented under the proper rigidity of the flexible tube, and the occurrence and progress of cracks in the flexible tube due to the vibration of the flexible tube in the axial direction and the direction orthogonal thereto, The non-directional, superior reinforcing function in each direction of the reinforcement can prevent and bring about a significant increase in durability.

By the way, this flexible tube is filled with an elastic material mixed with a short fiber reinforcing material by transfer molding, injection molding, or the like, for example, in a mold having four or more injection holes at predetermined intervals in the circumferential direction. Since it can be manufactured by the above method, it is extremely easy to manufacture, and the wall thickness, the internal structure, etc. of the flexible tube can be made sufficiently uniform over the whole.

Here, when the aspect ratio of the short fiber reinforcing material is 200 to 600, the physical properties such as elastic modulus, tensile strength, and elongation are substantially uniform in any direction, which is suitable without orientation. A flexible tube will be provided. That is, when the aspect ratio is less than 200, the reinforcing material has a strong tendency to be oriented when manufacturing a flexible tube by transfer molding, injection molding, or the like. On the other hand, when the aspect ratio exceeds 600, the reinforcing material Due to the entanglement of, the uniformity of the physical properties of the flexible tube is impaired.

(Example) Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a perspective view and a front view showing a part of a cross section of an embodiment of the present invention, and 11 in the figure shows the entire flexible tube.

The flexible tube 11 of this example comprises a bellows-like portion 12 located at the center in the length direction and smooth cylindrical portions 13 continuous at both ends thereof, and the flexible tube 11 is made of an elastic material. A short-fiber reinforcing material 15 embedded without being oriented in 14 is provided.

Here, such a flexible tube 11 is, for example, formed on one end surface or both end surfaces in the length direction of a mold cavity for molding the flexible tube 11 in a direction orthogonal to each surface thereof and in the circumferential direction. Formed from four or more injection holes with a predetermined spacing, or in the inner or outer peripheral surface of the mold cavity, in the direction orthogonal to each surface, and also with a predetermined spacing in the circumferential direction. From the above injection holes, preferably a short fiber reinforcing material 15 having an aspect ratio of 200 to 600, which is also preferably 3
It can be formed by filling an elastic material mixed in a ratio of ˜30 phr into a mold cavity by transfer molding, injection molding or the like.

Here, in particular, when the flexible tube 11 includes the bellows-like portion 12 as shown in the drawing, it is possible to inject the elastic material from the injection hole provided in the end surface of the mold cavity.
This is suitable for effectively preventing the orientation of the reinforcing material 15 in the bellows-like portion 12 and providing the physical properties of the portion uniformly.

Here, the amount of the short fiber reinforcing material 15 added to the elastic body of the flexible tube 11 is set to 3 to 30 phr, while if it is less than 3 phr, a sufficient reinforcing effect cannot be obtained.
If it exceeds phr, the rigidity of the flexible tube 11 becomes too high and the durability is lowered, and the short fiber reinforcing material 15 hinders appropriate transfer molding, injection molding and the like. .

And, of course, the material of the short fiber reinforcing material 15 here may be cellulose short fibers as described in the prior art, but particularly when the flexible tube 11 is used at high temperature, Young's modulus of short cellulose fibers is 170
With the decrease to about 130 g / denier at 0 ° C., the thermal deterioration of the short fibers is severe, and the short fiber reinforcing material 15 cannot provide a sufficient reinforcing effect.
Preferably, the Young's modulus at 170 ° C. is 350 g / denier or more, and the short fiber reinforcing material 15 is formed of an aromatic polyamide fiber (Kevlar (trademark) or the like), so that the flexible tube 11 has high Guarantees the elastic modulus. That is, as described above, the short fiber reinforcement 15 having a high Young's modulus is used.
When using, even if it is embedded in a non-oriented state,
A sufficiently high elastic modulus at a high temperature can be obtained as compared with the case where the cellulose short fibers are oriented, and the high temperature durability is sufficiently improved.

Further, as the elastic body 14 in which the short fiber reinforcing material 15 as described above is embedded, it is also possible to use general-purpose rubber such as butadiene rubber, natural rubber, nitrile butadiene rubber, and styrene butadiene rubber. Since the rubber of the flexible tube 11 deteriorates at a relatively high temperature to lower the durability of the flexible tube 11, the elastic body 14 of the flexible tube 11 used under high temperature includes fluororubber, silicone rubber, hydrogenated nitrile. Butadiene rubber, acrylic rubber, ethylene / acrylic ester copolymer, ethylene / vinyl acetate / acrylic ester terpolymer, chlorosulfonated polyethylene, epichlorohydrin, ethylene / propylene copolymer, ethylene / propylene / diene terpolymer , Isobutene-isoprene rubber, or modified products thereof, or any of them, and 50% It is preferable to select a blend with the other polymers below.

According to the flexible tube 11 having such a configuration, since the short fiber reinforcing material 15 is embedded in the elastic body 14 without being oriented,
Physical properties such as elastic modulus, tensile strength, and elongation of the flexible tube 11 can be made substantially uniform in any direction, and furthermore, they can be effectively enhanced.
Upon the action of internal pressure and / or vibration there, it is possible to effectively prevent the occurrence of cracks in the flexible tube 11 oriented in the orientation direction of the short fiber reinforcing material, resulting in a significant improvement in durability and vibration damping. It is possible to fully exert the function and enhance the riding comfort in the vehicle.

In addition, since the flexible tube 11 can be efficiently manufactured with sufficient accuracy by using transfer molding, injection molding, etc., the flexible tube cost can be reduced, and the flexible tube can be made flexible. Homogenization of the entire tube can be provided.

Here, both the elastic body 14 and the short fiber reinforcement 15 are
It has been confirmed that a flexible tube 11 having excellent heat aging resistance and high temperature durability can be obtained under the action of the non-oriented short fiber reinforcing material 15 when it has excellent heat resistance. .

FIG. 2 is a partial sectional front view showing another embodiment of the present invention. In this example, a rigid ring 16 made of metal, synthetic resin, or the like is fitted to each constricted portion of the bellows-like portion 12. According to this example, the flexible ring is acted by the action of the rigid ring 16. Its bellows under the action of internal pressure on 11
The increase in diameter of 12 can be effectively prevented.

The durability of the flexible tube according to the present invention and a comparative example with that of a conventional product will be described below.

[Comparative example]

Here, both the invented product and the conventional product are flexible pipes including a bellows-like portion as shown in FIG. 1, and for each of them, the outer diameter change rate in a high temperature atmosphere and the repeated deformation in the expansion / contraction direction. And the durability were measured. The results are shown below. .

Here, the rate of change in outer diameter is 170 ° C with an internal pressure of 1 kg / cm ² enclosed.
Shows the rate of increase in outer diameter after being left for 500 hours in the atmosphere of
Durability indicates the number of times of endurance when the flexible tube was repeatedly expanded and contracted over ± 25% of its length in an atmosphere at 170 ° C with an internal pressure of 1 kg / cm ² enclosed.

According to this table, in the invention products 1 to 4 in which the aramid fiber was embedded without being oriented, the rate of change in outer diameter was found to be somewhat larger than that in the case where it was oriented in the circumferential direction,
Since it is a very small value when compared with the conventional products 1 and 2, it is understood that the non-oriented aramid fiber can sufficiently exert the flexible tube reinforcing function even at high temperature,
In addition, from the viewpoint of durability, the invention products 1 to 4 are remarkably superior to the conventional product 1.2 as well as the case where the aramid fibers are oriented because the aramid fibers are non-oriented. It turns out that it can bring about different results.

(Effect of the invention) Therefore, according to the present invention, by making the physical properties of the flexible tube sufficiently uniform in any direction, the internal pressure of the flexible tube, and the expansion and contraction direction of the flexible tube, It is possible to give extremely excellent durability against a wide variety of repeated deformations and displacements such as bending directions. Moreover, those displacements are effective with proper rigidity, mainly by the action of the bellows-like part. Can be absorbed into.

[Brief description of drawings]

 1 and 2 are diagrams showing an embodiment of the present invention, FIG. 3 is a schematic diagram showing an application example of a flexible tube, and FIGS. 4 and 5 are diagrams showing conventional examples. 11: Flexible tube, 12: Bellows portion 13: Smooth tubular portion, 14: Elastic body 15: Short fiber reinforcement

Claims (1)

[Claims] 1. A flexible tube having an elastic body as a main body and a bellows-shaped portion in an intermediate portion, wherein the short fiber reinforcing material is embedded in the elastic body without being oriented.