JP2000179756A - Flexible pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a bending angle and the added quantity of short fiber reinforcing material most appropriately taking account of cost, durability and manufacture by adding the short fiber reinforcing material at a rate of specified value or less into elastic body material in a flexible pipe formed of an elastic body with a smooth part on one end side bent at a specified bending angle. SOLUTION: A flexible pipe 1 is provided with a bellows part 2 at the center part in a lengthwise direction and smooth parts 3, 4 connected to both ends, and the axis of the smooth part 3 on one end side is bent at a specified bending angle α from the axis of the other part. The flexible pipe 1 is formed adding short fiber reinforcing material 6 in elastic body material 5. As the short fiber reinforcing material 6, it is ideal to use polybenzazole fiber or aromatic polyamide fiber. In the case of setting the optimum added quantity of the short fiber reinforcing material 6 in relation to the bending angle α, it is ideal to set the short fiber reinforcing material 6 to 10 phr or less in the elastic body material 5 when the bending angle α is less than 15 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an application requiring a vibration damping function under a high temperature condition, for example, mounted between a supercharger of an automobile engine and an intercooler and between an intercooler and an engine. The present invention relates to a flexible tube used for supplying engine supply air and for preventing transmission of engine vibration to a vehicle body and capable of exhibiting excellent durability.

[0002]

2. Description of the Related Art When used as a conventional air supply hose for an automobile engine, one end must be bent due to the arrangement in the engine, and pressure is applied to the hose or vibration is input. A bellows-shaped part was provided in the middle of the process. Also, to be used under high temperature conditions,
A hose, that is, a flexible tube has been formed from a material obtained by mixing a short fiber reinforcing material with an elastic material. For example, natural rubber is used as an elastic material, and polybenzazole-based fibers (P
What mixed with (BO) and aromatic polyamide (for example, Kevlar) fiber etc. is known.

[0003]

Since the short fiber reinforcing material is more expensive than the elastic material, it is desirable to reduce the amount of addition as much as possible from the viewpoint of cost. However, if the bending angle at the time of bending one end is large, the durability is reduced. Therefore, it is necessary to increase the addition amount of the short fiber reinforcing material. However, the fact that the bending angle is large means that from the manufacturing point of view, demolding from the core of the mold must be considered, and those with a small amount of short fiber reinforcement are easily demolded. However, there was a problem that demolding became difficult with a large amount of addition.

[0004] Therefore, the present invention provides cost, durability,
It is an object of the present invention to provide a flexible tube in which the bending angle and the addition amount of the short fiber reinforcing material are optimized in consideration of the manufacturing aspect.

[0005]

In order to achieve the above-mentioned object, the present invention comprises a bellows-like portion at the center in the length direction and smooth portions continuous at both ends thereof, and a smooth portion at one end. The axis of one part is 0 ° <α <in a flexible tube mainly composed of an elastic body bent at a bending angle α from the axis of another part.
In the case of 15 °, the short fiber reinforcing material should be 10
It is an addition amount of phr or less. Also, 15 ° <α
When <60 °, one short fiber reinforcing material is used in the elastic body forming material.
The amount added was in the range of 5 to 20 phr.

[0006]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

In the embodiment shown in FIG. 1, a bellows-like portion 2 is provided at the center in the longitudinal direction, and smooth portions 3 and 4 continuous with both ends thereof. The flexible tube 1 is bent at an angle α from another axis. The flexible tube 1 is made of an elastic body, and is formed by adding a short fiber reinforcing material 6 to the elastic body forming material 5. Further, a ring 7 is fitted into the constricted portion of the bellows-like portion 2 to prevent the diameter of the bellows-like portion 2 from increasing. As the ring 7, an O-ring made of an elastic material can be used. The short fiber reinforcing material 6 may be added to the elastic material forming the ring 7.

As the elastic body forming material 5, general-purpose rubbers such as butadiene rubber, natural rubber, nitrile butadiene rubber, and styrene butadiene rubber can be used.
Since these rubbers deteriorate at a relatively high temperature and deteriorate the durability of the flexible tube 1 relatively early, the elastic body forming material 5 of the flexible tube 1 used at a high temperature may be fluorine rubber, silicon rubber, or the like. , Hydrogenated nitrile butadiene rubber, acrylic rubber, ethylene / acrylic ester copolymer, ethylene /
Vinyl acetate / acryl ester terpolymer, chlorosulfonated polyethylene, epichlorohydrin, ethylene /
It is preferable to select a propylene copolymer, an ethylene-propylene-diene terpolymer, an isobutene-isoprene rubber or a modified product thereof, or a product obtained by blending any of them with 50% or less of another polymer.

As the short fiber reinforcing material 6 to be added to the elastic body forming material 5, a polybenzazole fiber (PBO fiber), for example, polyparapolyylene benzobisoxazole (cis type) or an aromatic polyamide fiber, for example, Kevlar (registered trademark) fibers can be suitably used.

When the bending angle α shown in FIG. 1 increases, the durability of the flexible tube 1 deteriorates. Because, as shown in FIG.
When a pressure is applied to the inside of the flexible tube 1 at a high temperature, a larger force is applied as an integral force of the pressure to the side having a larger curvature at the bent portion (indicated by a dotted line in FIG. 2). Deform. This deformation also affects the bellows-like portion 2. In other words, the bellows-like portion 2 attempts to absorb the lengthened distance due to the bent portion being raised. When the internal pressure input is repeatedly applied, the bellows-like portion 2 is distorted, and particularly tensile strain is generated, which causes cracks and the like. Therefore, in order to increase the rigidity of the bent portion of the flexible tube 1 and suppress deformation, the short fiber reinforcing material 6 is used.
It is conceivable to increase the addition amount of, but simply increasing the addition amount causes disadvantages in cost and production. Then, the present inventors repeated various experiments to find out the optimal amount of the short fiber reinforcing material 6 in relation to the bending angle α. As a result, it has been found that when the bending angle α is less than 15 °, it is preferable to add the short fiber reinforcing material 6 to the elastic body forming material 5 in an amount of 10 phr or less. Here, "phr" is a ratio based on 100 parts by weight of the polymer. When the bending angle α is more than 15 ° and less than 60 °, it is determined that it is preferable from the viewpoints of cost and production to add the short fiber reinforcing material 6 in the range of 15 phr to 20 phr. did.

The optimum range of the addition amount of the short fiber reinforcing material 6 in relation to the bending angle α as described above has been found by the following experiment. That is, a fluid pressure of 0 to 0.15 MPa was repeatedly applied to the inside of the flexible tube 1 at an ambient temperature of 150 ° C., and the durability conditions of each sample were observed. In this case, pressure was applied at 0 to 0.15 MPa once a second. The results of the durability evaluation of these samples 1 to 8 are as shown in the following table. In the comparative example, the bending angle α was 15 °, and the amount of the short fiber reinforcing material 6 was 3 phr. In these samples 1 to 8 and the comparative example, acrylic rubber was used as the elastic body forming material 5 and Kevlar fiber of 23 g / d per unit weight was used as the short fiber reinforcing material 6.

[0012]

[Table 1]

When used as a flexible tube 1 for connecting an intercooler of an automobile and an engine, the number of times of durability is one.
No problem occurs if the number is more than one million times. Here, the short fibers in the short fiber reinforcing material 6 were Kevlar, having a diameter of about 12 μm and a length of 2.0 to 6.0 mm. The short fiber reinforcing material 6 is randomly embedded in the elastic body forming material 5 so as not to be oriented in a predetermined direction.

FIG. 3 shows a mold 10 for molding the flexible tube 1 as shown in FIG. 1. A cylindrical core 12 is inserted into a cylindrical space 11 formed in the mold 10. First and second cavities 13 and 14 communicating with each other are formed on the distal end surface side and the outer peripheral surface side of the core 12. A molding material injecting runner 15 is provided near the center of the distal end surface of the core 12, in the illustrated example, at the center position. Further, a fluid introduction path 16 for air or the like is formed in the core 12, and a fluid valve 17 is provided at the distal end side of the fluid introduction path 16 so as to constantly urge the hole facing the cavity 13. It is. Runner 1
The position of 5 may be a position indicated by a broken line instead of a portion indicated by a solid line. That is, the position of the runner 15 can be moved according to the curvature of the curved portion of the molded product. In the case of having a curved portion as shown in FIG. 3, the distance from the runner 15 to the place where the bellows-like portion 2 is formed is made equal so that the injected molding material can simultaneously reach the end of the cavity 14 by a broken line. Is desirable.

Using a mold 10 as shown in FIG. 3, a molding material is injected into a cavity 13 from a runner 15. This cavity 13 becomes a disk-shaped gate. The molding material injected into the cavity 13 is radially diffused and flows from the outer peripheral edge of the core 12 to the cavity 14. Further, when the molding material flows into the cavity 14 and the molding material fills the cavities 13 and 14, the molding material is vulcanized. After vulcanization molding, the mold 10 is opened and the molded product and the core 12 are taken out. At this time, a molded article is released from the core 12 by blowing out a fluid such as air from the fluid introduction path 16 toward the distal end surface of the core 12. At this time, the fluid valve 17
Is extruded by the pressure of the fluid in the right-hand direction below the drawing, and is blown into the inside of the molded product from a gap created by the fluid. When fluid such as air is sent inside the molded product,
The molded product is released from the core 12.

According to the above-described molding method, the molding material is first supplied from the runner 15 to the disk-shaped cavity 13.
Therefore, several welds along the axial direction do not occur, and the mixed short fiber reinforcing material 6 is embedded uniformly and without being oriented in a specific direction. The molded flexible tube 1 embeds a short fiber reinforcing material 6 such as PBO fiber or Kevlar fiber in the elastic body forming material 5 without being oriented in a specific direction. The physical properties such as modulus, tensile strength and elongation can be made substantially uniform in any direction, and they can be effectively increased. Flexible tube 1 oriented in the direction of orientation of fiber reinforcement 6
Cracks can be effectively prevented, the durability can be significantly improved, and the anti-vibration function can be sufficiently exhibited.

The embodiment shown in FIGS. 4 and 5 shows a flexible tube 1 of a type in which the smooth portion 3 is not curved (α = 0 °) and a mold for molding the same. The molding material is injected into the cavity 14 from the cavity 13 serving as a disk-shaped gate.

FIG. 6 shows that flexible tubes 1 are mounted between a supercharger 21 and an intercooler 22 of an automobile engine 20 and between the intercooler 22 and the engine 20, respectively. This is an example in which it is used as a function to prevent transmission of engine vibration to the vehicle body.

A bellows-shaped portion 2 is provided at the center in the length direction, and smooth portions 3 and 4 are provided at both ends thereof. The elastic portion is bent at an angle α from the axis of the smooth portion at one end. In a flexible tube mainly composed of a body, when 0 ° <α <30 °, when the short fiber reinforcing material 6 is added in an amount of 20 phr or less in the elastic body forming material 5, Y is used as the short fiber reinforcing material 6 (unit). phr), where X is an angle (specific angle of the bending angle α), the addition amount (Y) of the short fiber reinforcing material 6 represented by the following equation. Y ≧ 0.40X (1)

When the bending angle α is 30 ° <α <60 °
In the case of, the short fiber reinforcing material 6 is added to the elastic body forming material 5 by 20 ph.
When the addition amount is equal to or less than r, the addition amount Y of the short fiber reinforcing material 6 for each angle X is represented by the following equation. Y ≧ 0.05X + 10.5 (2)

The addition amount Y represented by the above formulas (1) and (2) is a region indicated by cross hatching in the graph of FIG. Those in this area had a durability count of 1,000,000 times or more.

Further, when the upper limit of the addition amount Y is Y ≦ 0.30X + 7.5... (3) or Y ≦ 0.04X + 14.8. This is an area displayed by hatching, which is advantageous in terms of cost while ensuring durability.

[0023]

As described above, according to the present invention, when the bending angle α is 0 ° <α <15 °, the short fiber reinforcing material is added to the elastic body forming material in an amount of 10 phr or less, and the bending is performed. When the angle α exceeds 15 ° and is less than 60 °, the short fiber reinforcing material is added in the range of 15 phr to 20 phr in the elastic body forming material. The amount of the short fiber reinforcing material can be set.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flexible tube.

FIG. 2 is a cross-sectional view illustrating a decrease in durability when a bending angle is large.

FIG. 3 is a sectional view showing a mold for molding the flexible tube of FIG. 1;

FIG. 4 is a partially broken front view showing the flexible tube when the bending angle is 0 °.

FIG. 5 is a diagram showing a cavity portion and a runner of a mold for manufacturing the flexible tube of FIG. 4;

FIG. 6 is a simplified diagram showing an example in which this flexible tube is provided at a location of an automobile engine.

FIG. 7 is a graph showing the relationship between the amount of short fiber reinforcement added and the bending angle.

FIG. 8 is a graph showing an example in which the same upper limit as in FIG. 7 is provided.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible tube 2 Bellows-like part 3, 4 Smooth part 5 Elastic body forming material 6 Short fiber reinforcement

Claims (7)

[Claims] 1. A bellows-like portion is provided at a central portion in a longitudinal direction, and a continuous smooth portion is provided at both ends of the bellows portion. A flexible tube mainly comprising a bent elastic body, characterized in that a short fiber reinforcing material is added in an amount of 10 phr or less in an elastic body forming material when 0 ° <α <15 °. . 2. An elastic body which is provided with a bellows-like portion at the center in the longitudinal direction and a continuous smooth portion at both ends thereof, and which is bent at a bending angle α from the axis of the smooth portion on one end side. A flexible tube characterized in that, when 15 ° <α <60 °, a short fiber reinforcing material is added in an amount within a range of 15 to 20 phr in the elastic body forming material when 15 ° <α <60 °. 3. An elastic body which is provided with a bellows-like portion at the center in the longitudinal direction and a continuous smooth portion at both ends thereof, and which is bent at a bending angle α from the axis of the smooth portion on one end side. In a flexible tube mainly used, when 0 ° <α <30 °, the short fiber reinforcing material is not more than 20 phr in the elastic body forming material, and Y ≧ 0.43X−1.5 (Y = short fiber reinforcing material: phr
(X = angle). 4. The upper limit of the amount of addition is Y ≦ 0.23X + 7 (Y = short fiber reinforcing material: phr X =
The flexible tube according to claim 3, wherein the angle is: 5. The upper limit of the amount of addition is Y ≦ 0.083X + 11.5 (Y = short fiber reinforcing material: ph
The flexible tube according to claim 3, wherein rX = angle. 6. An elastic body which is provided with a bellows-like portion at the center in the longitudinal direction and a continuous smooth portion at both ends thereof, and which is bent at an angle α from an axis of the smooth portion at one end. In the flexible tube mainly used, when 30 ° <α <60 °, the short fiber reinforcing material is 20 phr or less in the elastic body forming material, and Y ≧ 0.067X + 9.5 (Y = short fiber reinforcing material: phr)
(X = angle). 7. The flexible tube according to claim 1, wherein one of a polybenzazole-based fiber and an aromatic polyamide-based fiber is used as the short fiber reinforcing material.