JP2006064148A - Metal bellows pipe composite hose - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal bellows pipe composite hose having excellent durability as a whole by improving durability in repeated bending flexure in addition to durability in repeated application of inner pressure. <P>SOLUTION: This metal bellows pipe composite hose 10 comprises a metal bellows pipe 20, a rubber filler material layer 22, and reinforcement layers 24 and 25, to which a preliminary pressurization process of adding higher inner pressure than inner pressure applied in real use is conducted to plastically deform the metal bellows pipe 20 so as to make the reinforcement layer 24 tensed prior to real use. Prior to the preliminary pressurization process, the radius of curvature at a ridge part 29 in the metal bellows pipe 20 is set to be smaller than the radius of curvature at a valley part 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a metal bellows having a metal bellows tube as a transport fluid permeation barrier layer, which can be suitably used for automobile fuel transportation, refrigerant transportation, transportation of battery fuel such as hydrogen gas used in fuel cells, and others. It relates to a tube composite hose.

Conventional hose for transportation of automobile fuel (fuel for engines such as gasoline) with good vibration absorption and assembly, for example, NBR / PVC (acrylonitrile butadiene rubber and poly In recent years, regulations on the permeation of fuel for automobiles, etc., have been stricter from the viewpoint of global environmental protection, and the regulations are expected to be further strengthened in the future.
Therefore, further permeation resistance is required in such a fuel transport hose.

Further, in a transport hose for hydrogen gas or the like used in a fuel cell or a transport hose for a carbon dioxide refrigerant, extremely high permeation resistance is required for the transport fluid such as hydrogen gas or carbon dioxide gas.
In response to these requirements, it is difficult to satisfy the required performance with a hose composed only of an organic material such as rubber or resin.

In view of the above, a metal bellows tube composite hose having a metal bellows tube composited and having this as a transport fluid permeation barrier layer has been studied.
For example, Patent Document 1 below discloses this type of metal bellows tube composite hose.

  By the way, the metal bellows tube has flexibility due to the bellows shape, that is, the shape effect, and since the material itself is a metal, it does not have elasticity unlike rubber or the like.

  Therefore, in the case of such a metal bellows tube composite hose, when the metal bellows tube is actually used, the metal bellows tube is repeatedly deformed, so that the metal bellows tube is easily damaged by fatigue.

  As a result of detailed investigations of the fatigue fracture of the metal bellows pipe by the present inventors, the fatigue fracture due to the repetitive action of the internal pressure cracks at the top of the metal bellows pipe, and the metal bellows pipe is prone to fatigue fracture. As for the fatigue fracture due to the repeated bending deformation based on the flexibility of the crack, it has been found that there is a fact that cracks are easily generated and broken at the bottom of the valley.

Therefore, the present inventors have applied pre-pressurization to the metal bellows tube composite hose before actual use (before actual use) while studying countermeasures against fatigue fracture based on repeated action of internal pressure. Thus, knowledge that can dramatically improve the durability has been obtained and proposed in a previous patent application (Japanese Patent Application No. 2004-095542).
The contents are as follows.

FIG. 5 shows an example of a metal bellows tube composite hose to be applied.
In the figure, 200 is a metal bellows tube composite hose (hereinafter simply referred to as a hose), and 202 is a metal bellows tube as the innermost layer.
206 is a rubber filler layer (elastic filler layer) that fills the outer peripheral valley space 208 between the peaks 204 and 204 in the metal bellows tube 202, 210 is a reinforcing layer on the outer periphery side, and 212 is an outermost layer. As an outer surface rubber layer (cover rubber layer).

  Here, the rubber filler layer 206 is a layer having a function of filling the valley space 208 of the metal bellows tube 202 and suppressing excessive deformation of the metal bellows tube 202, and the reinforcing layer 210 is a reinforcing wire material such as organic fiber. This layer is formed by braiding the bellows metal tube 202, and when the internal pressure is applied to the bellows metal tube 202, the pressure is applied to the metal bellows tube 202, that is, the hose 200.

  Here, FIG. 5 (A) shows a state at the time of manufacturing the hose. On the other hand, the one disclosed in this prior application is higher than the pressure applied in actual use in advance before the hose 200 is actually used. A pre-pressurizing process for applying an internal pressure is performed.

  In this way, the peak portion 204 of the metal bellows tube 202 fills the valley space 208 by applying a high internal pressure to the metal bellows tube 202 (a high pressure that causes the metal bellows tube 202 to undergo plastic deformation beyond the yield point). The rubber filler layer 206 is swelled and deformed (plastic deformation) so as to be pushed to the outer peripheral side (see FIG. 5B), whereby the outer reinforcing layer 210, more specifically the reinforcing wire, is in a tension state. As a result, there is no loosening or play of the reinforcing wire, and as a result, the reinforcing pressure resistance effect of the reinforcing layer 210 is instantaneously exerted on the metal bellows tube 202 when the internal pressure acts on the metal bellows tube 202 in the actual use state. Thus, the deformation of the metal bellows tube 202 is restricted, whereby the fatigue fracture due to the repetitive action of the internal pressure of the metal bellows tube 202 is suppressed, and the durability is drastically improved. .

  By the way, when pre-pressurization treatment is performed on the hose 200 before actual use in this way, durability against repeated action of internal pressure is improved, but on the other hand, durability against repeated bending is actually decreased. Became clear in subsequent studies.

  In pursuit of the cause, the decrease in durability against such repeated bending deformation is caused by the shape change of the valley portion so that the radius of curvature R is smaller than the initial shape as a result of the pre-pressurization treatment. It turns out that it is brought about.

  The effect of improving the durability against the repetitive action of the internal pressure by the preliminary pre-pressurization treatment is that the rubber filler layer 206 filling the valley space 208 as described above moves to the outer peripheral side with the bulging deformation of the peak portion 204. As a result, the reinforcing layer 210 is put in a tension state from the beginning, and the loosening and loosening of the reinforcing wire material that has been initially generated disappears. As a result, as shown in FIG. 5C, the radius of curvature of the valley portion 214 becomes small, and when the metal bellows tube 202 is repeatedly bent and deformed, It has been found that a large stress is applied to the bottom, and cracks are likely to occur at the bottom of the valley 214, which results in a decrease in durability against repeated bending deformation.

  In the metal bellows tube 202, the maximum stress is generated by the internal pressure action at the top of the peak portion 204, while the maximum stress is generated by bending deformation at the bottom of the valley portion 214. Suppressing fatigue fracture at the bottom of the top and trough 214 is a key point for improving durability against repeated action of internal pressure and improving durability against repeated bending deformation.

The object of the present invention is to improve both the durability against repeated action of internal pressure and the durability against repeated bending deformation in the metal bellows tube composite hose.
In addition, what improves the durability of a metal bellows tube is disclosed in the following Patent Document 2 and Patent Document 3.

Here, what is disclosed in Patent Document 2 is to apply an internal pressure to the metal bellows and extend it in the axial direction to expand the pitch, and to increase the durability by work hardening at that time, inevitably The axial length of the metal bellows tube will be different.
Further, the one disclosed in Patent Document 3 is that the shape of the bellows part in the metal bellows tube is changed from a U-shaped cross section to an S-shaped cross section, and the durability is enhanced by the shape effect. Differ in the means for improving durability.

JP 2001-182872 A JP-A-57-86688 JP-A-11-159616

  In view of the circumstances as described above, the present invention provides a metal bellows tube composite hose having excellent durability as a whole by increasing durability against repeated bending deformation in addition to durability against repeated action of internal pressure. It was made for the purpose.

  Thus, according to the first aspect of the present invention, (b) a metal bellows tube as a transport fluid permeation barrier layer, and (b) a gap between the valleys on the outer periphery side between the peaks of the metal bellows tube are filled. An elastic filler layer and (c) a reinforcing layer formed by braiding a reinforcing wire on the outer peripheral side of the elastic filler layer, and prior to actual use, an internal pressure higher than the internal pressure applied during the actual use. A metal bellows tube composite hose that is used after being subjected to a pre-pressurizing treatment that plastically deforms the metal bellows tube by loading the reinforcing layer and makes the reinforcing layer in a tension state, before the pre-pressurizing treatment The metal bellows tube is characterized in that the radius of curvature of the peak is smaller than the radius of curvature of the valley.

  According to a second aspect of the present invention, in the first aspect, the curvature radius of the peak portion is 2/3 or less with respect to the curvature radius of the valley portion.

Effects and effects of the invention

As described above, according to the present invention, the shape of the metal bellows tube before the pre-pressurizing process is such that the curvature radius of the peak portion is smaller than the curvature radius of the valley portion.
In other words, the metal bellows tube used for conventional piping has the same shape at the time of manufacture in both the crests and troughs. The shape before the pressure treatment is such that the curvature radius of the peak portion is smaller than the curvature radius of the valley portion. When pressure treatment is performed to bulge and deform the peak, the curvature radius of the peak and the curvature radius of the valley become close, that is, the shape of the peak and the shape of the valley become close to the same shape, Therefore, the durability against repeated bending deformation can be effectively enhanced together with the durability against the repeated action of the internal pressure.

In addition, the radius of curvature of the valley is larger than the peak of the metal bellows tube at the time of manufacture, so that the insertion of the elastic filler layer into the valley space is improved and elastic filling is ensured to every corner of the valley space. The material layer can be filled, and the effect of further improving or stabilizing the quality of the product can be obtained.
In the present invention, the shape of the crests and troughs includes those that can be said to be substantially arcuate in addition to the case where they are strictly arcuate.

In the present invention, it is desirable that the curvature radius of the peak portion is 2/3 or less, particularly 1/3 or less with respect to the curvature radius of the valley portion (claim 2).
By having such a shape, when a large pressure is applied so as to later plastically deform the peak portion of the metal bellows tube by a pre-pressurization process, the curvature radius of the peak portion and the curvature radius of the valley portion are made closer. be able to.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a metal bellows tube composite hose according to an embodiment of the present invention. However, FIG. 1 shows the state before the subsequent pre-pressurizing process.
In FIG. 1, 10 is a metal bellows tube composite hose (hereinafter simply referred to as a hose), 12 is a hose body, and 14 is a fitting fitting attached to the end of the hose body 12.
The joint fitting 14 has a pipe-like insert fitting 16 and a sleeve-like socket fitting 18, and the socket fitting 18 is fixed to the end portion of the hose body 12 by being caulked in the diameter reducing direction. Has been.

  The hose 10 has a metal bellows tube 20 in its innermost layer, a rubber filler layer 22 as an elastic filler layer on the outer peripheral side of the metal bellows tube 20, and a first reinforcing layer 24 and an intermediate rubber layer 27 on the outer peripheral side. The second reinforcing layer 25 and the outer rubber layer (cover rubber layer) 26 as the outermost layer are laminated in order.

As shown in FIG. 1B, the metal bellows tube 20 has a bellows portion 28 and a straight shape portion 30 that forms a straight tube at the end, and the insert fitting is placed inside the straight shape portion 30. 16 is inserted.
The innermost metal bellows tube 20 serves as a permeation barrier layer for the transport fluid, and is provided with flexibility by the bellows portion 28.

The rubber filler layer (non-foamed solid rubber layer) 22 fills the valley space 32 on the outer peripheral side between the adjacent peak portions 29 and 29 in the bellows portion 28 as shown in FIG. This is a layer that suppresses the bulging deformation of the peak portion 29 when the internal pressure acts on the bellows portion 28.
In the present embodiment, the rubber filler layer 22 is in a state of completely filling the valley space 32 until reaching the top of the peak portion 29, and the thickness between the top of the peak portion 29 and the reinforcing layer 24 is 0. It is provided with a thickness of 5 mm or less.

  On the other hand, the first and second reinforcing layers 24 and 25 are layers for ensuring a pressure resistance, and the intermediate rubber layer 27 between them prevents the displacement and wear between the first reinforcing layer 24 and the second reinforcing layer 25. The outer rubber layer 26 serving as an outermost layer serves to protect the second reinforcing layer 25.

In the present embodiment, the thickness of the metal bellows tube 20 is preferably 0.5 mm or less because of the required flexibility and flexibility.
On the other hand, 0.1 mm or more is desirable from the workability of metal tube processing.
The material of the metal bellows tube 20 can be steel, aluminum or aluminum alloy, copper or copper alloy, nickel or nickel alloy, titanium or titanium alloy, and the like. Although it is suitably selected from durability, metal pipe workability, etc., stainless steel can be particularly preferably used.

In addition, the material of the reinforcing wire of the first and second reinforcing layers 24 and 25 can be a reinforcing thread made of organic fiber or other various materials, and a metal wire can be used as necessary.
In this embodiment, the elastic filler layer is the rubber filler layer 22. However, it is possible to use an elastic material other than rubber, such as a thermoplastic elastomer, depending on circumstances.

As shown in detail in FIG. 2, in this embodiment, the shape of the metal bellows tube 20, specifically the bellows portion 28, is the following shape before the subsequent pre-pressurization treatment, that is, the radius of curvature of the valley portion 31 ( The radius of curvature (R2 ₀ ) of the peak portion 29 is smaller than that of R1 ₀ ).
In FIG. 2B, OD represents the outer diameter of the bellows portion 28, ID represents the inner diameter, Pi represents the pitch, and t represents the thickness.

FIG. 3 shows a state after applying a pre-pressurizing process to the hose shown in FIGS. 1 and 2 prior to actual use.
Here, the pre-pressurization treatment is performed at a pressure higher than the internal pressure applied from the transport fluid when the hose 10 is actually used, specifically, a high pressure that causes the peak portion 29 in the metal bellows tube 20 to be plastically deformed beyond the yield point. In addition, the peak portion 29 is bulged and deformed, thereby applying a pushing force to the outer side (radially outer side) with respect to the rubber filler layer 22 filling the valley space 32 so that the first reinforcing layer 24 is in a tension state in advance. In other words, the first reinforcing layer 24 is sufficiently formed by this pre-pressurizing process in order to eliminate the looseness and play that were initially generated in the first reinforcing layer 24 and to put the first reinforcing layer 24 in a tension state. It will be used for actual use in a state in which a state of tension is maintained.
At this time, as shown in FIG. 3, the peak portion 29 has a peak height on the first reinforcing layer 24 side, and the rubber between the peak portion 29 and the first reinforcing layer 24 removed at that time The filler layer 22 enters between the adjacent peak portions 29 and 29 where the peak height is partially increased.

  Thus, by performing such pre-pressurization treatment, when an internal pressure is applied to the metal bellows tube 20 during actual use of the hose 10, the internal pressure is immediately transmitted to the first reinforcing layer 24, and the applied pressure is applied. Is received by the first reinforcing layer 24, and the reinforcing effect of the first reinforcing layer 24 restricts deformation of the metal bellows tube 20 during actual use.

In the present embodiment, the shape of the corrugated metal tube 20 prior to addition of the pre-pressure treatment as described above, the curvature of the ridges 29 radially (R2 ₀₎ is small relative to the valleys 31 radius of curvature (R1 ₀₎ As a result, the radius of curvature (R2) of the peak portion 29 is changed to the curvature radius of the valley portion 31 (R2) as shown in FIG. R1).

  As described above, according to the present embodiment, the shape of the peak portion 29 and the shape of the valley portion 31 are close to the same shape by the pre-pressurization treatment, and accordingly, in addition to the durability against the repetitive action of the internal pressure, The durability against repeated bending deformation can be effectively enhanced.

In addition, since the curvature radius (R1 ₀ ) of the valley portion 31 is larger than the curvature radius (R2 ₀ ) of the peak portion 29 in the metal bellows tube 20 at the time of manufacture, the insertability of the rubber filler layer 22 into the valley space 32 is improved. And the quality of the product is improved or stabilized.

In the present embodiment, it is desirable that the curvature radius (R2 ₀ ) of the peak portion 29 is 2/3 or less with respect to the curvature radius (R1 ₀ ) of the valley portion 31, and in particular, 1/3 or less. Is good.
With such a shape, when a large pressure is applied so as to plastically deform the peak portion 29 of the metal bellows tube 20 later in the pre-pressurizing process, the curvature radius (R2) of the peak portion 29 and the valley portion 31 The radius of curvature (R1) can be made closer.

Next, examples of the present invention will be described together with comparative examples.
1. Hose manufacture
[Comparative hose]
A metal bellows tube 20 was manufactured using SUS304 material. Here, the metal bellows tube 20 had the following shape, that is, an outer diameter (OD) of 9.7 mm, an inner diameter (ID) of 4.5 mm, a plate thickness (t) of 0.23 mm, and a pitch (Pi) of 2.0 mm.
In addition, the curvature radius of the initial peak part 29 and the trough part 31 before preliminary pressurization was the same, respectively, and was 0.5 mm.

Next, a rubber material (using EPDM) is extruded thereon to form a rubber filler layer 22, and the first and second reinforcing layers 24, 25 are braided with braid using aramid yarn as the reinforcing yarn, and reinforced. Layers 24 and 25 were formed. At that time, an intermediate rubber layer 27 was formed between the first reinforcing layer 24 and the second reinforcing layer 25.
Here, the pressure resistance design of the reinforcing layers 24 and 25 was about 80 MPa.
Next, the outer rubber layer 26 was extruded to cover the second reinforcing layer 25.
Thereafter, the hose body 12 was formed by vulcanization under conditions of 150 ° C. × 30 minutes.

Thereafter, joint fittings 14 were attached to both ends of the hose body 12. At this time, the fitting 14 was mounted and assembled to the hose body 12 with a design exceeding the withstand pressure of 80 MPa.
Thereafter, the internal pressure was introduced at a pressure increase rate of 10 MPa / min to increase the pressure to 60 MPa, and then the pressure was reduced slowly.
The shape of the bellows portion 28 after the pre-pressurizing process is as follows. Ridge portion R (curvature radius: same hereinafter): trough portion R = 0.5: 0.5 (mm) = 1: 1 before the pre-pressurizing treatment. However, after the pre-pressurization treatment of 60 MPa, the peak portion R: valley portion R = 0.75: 0.25 (mm) = 3: 1, the peak portion R was large and the valley portion R was small. .

[Example 1 hose]
Example 1 hose was produced in the same manner as in the comparative example.
However, the crest R and the trough R in the bellows portion 28 before the pre-pressurizing treatment were 0.4 mm and 0.6 mm, respectively.
In this Example 1 hose, the peak portion R: valley portion R = 0.6: 0.4 (mm) = 3: 2 by the subsequent pre-pressurization treatment, and the peak portion R is compared with the valley portion R. It was a little big.

[Example 2 hose]
Example 2 hose was produced in the same manner as described above.
However, in Example 2 hose, the initial crest R and trough R before the pre-pressurizing treatment were set to 0.25 mm and 0.75 mm, respectively. As a result, the peak portion R and the valley portion R become peak portion R: valley portion R = 0.5: 0.5 (mm) = 1: 1 after the pre-pressurization treatment, respectively. It became equivalent.

2. Durability Evaluation For durability evaluation, a combined bending-vibration tester as shown in FIG. 4 was used in consideration of vibration durability after assembly in an automobile.
In the figure, reference numeral 34 denotes a mounting base, which has a horizontal portion 36 and a vertical portion 38 that are perpendicular to each other.
A turntable 40 is provided at the upper end of the vertical portion 38 so as to be rotatable around a rotation shaft 42.
Here, the hose 10 having a free length of 1 = 300 mm excluding the joint fitting 14 is bent so as to have a bending radius R: 120 mm, and the joint fitting 14 at one end of the hose 10 is intersected with the horizontal portion 36 of the mounting base 34 at an intersecting angle of 90 degrees. On the other hand, the joint fitting 14 at the other end is fixed at an eccentric position on the outer peripheral portion of the turntable 40 at an intersecting angle of 90 degrees with respect to the turntable 40 (however, the joint fitting 14 is fixed to the turntable 40). Then, by rotating the turntable 40 at 450 rotations per minute, vibration of amplitude: ± 15 mm (30 mm for both swings) was applied to the end of the hose 10 in the vertical and horizontal directions.

This vibration test was performed in a state where an internal pressure of 10 MPa was applied to the hose 10, and durability was evaluated by occurrence of cracks in the metal bellows tube 20. Specifically, the determination of durability was made assuming that a crack occurred in the metal bellows tube 20 when the internal pressure was reduced, and this was defined as the durability time.
Further, as a final confirmation, the hose 10 was disassembled, and the presence or absence of cracks in the metal bellows tube 20 was visually confirmed.
The results are shown in Table 1.

As can be seen from the results in Table 1, the durability of both Example 1 and Example 2 is significantly improved as compared with the comparative example, and in particular, the durability of Example 2 is dramatically improved. Thus, no cracks were observed in the metal bellows tube 20 even after 400 hours.
In addition, although the comparative example, Example 1, and Example 2 each show three numerical values about the durable time in Table 1, this represents each of the results of three durability tests.

  Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention is applicable to various types of metal bellows tube composite hoses other than the above-described examples, and does not depart from the spirit thereof. It can be configured with various modifications.

It is sectional drawing of the metal bellows pipe composite hose which is one Embodiment of this invention. It is the figure which showed the principal part of the metal bellows pipe composite hose of FIG. It is the figure which showed the principal part of the metal bellows pipe composite hose of FIG. 1 in the state after a pre-pressurization process. It is explanatory drawing of the test method of the vibration endurance test in the Example of this invention. It is explanatory drawing for the background description of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Metal bellows pipe composite hose 20 Metal bellows pipe 22 Rubber filler layer 24 1st reinforcement layer 25 2nd reinforcement layer 28 Bellows part 29 Mountain part 31 Valley part 32 Valley part space R1 ₀ , R1, R2 ₀ , R2 Curvature radius

Claims (2)

(B) a metal bellows tube as a transport fluid permeation barrier layer; (b) an elastic filler layer that fills the outer space between the crests and crests of the metal bellows tube; A reinforcing layer formed by braiding a reinforcing wire on the outer peripheral side of the elastic filler layer, and prior to actual use, by applying an internal pressure higher than the internal pressure applied during the actual use, the metal bellows tube A metal bellows tube composite hose that is plastically deformed and used in a pre-pressurizing process in which the reinforcing layer is in a tension state, and before the pre-pressurizing process, the metal bellows pipe is A metal bellows tube composite hose characterized in that the radius of curvature is smaller than the radius of curvature of the valley.   2. The metal bellows tube composite hose according to claim 1, wherein a radius of curvature of the peak portion is 2/3 or less of a radius of curvature of the valley portion.

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