JP2016156465A - Brake hose - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake hose having a low expansion property and a low temperature anti-bending durability.SOLUTION: A brake hose is constituted by an inner layer 11 made of an aromatic polyamide resin having a bending elastic modulus of 1400 MPa or more and 2000 MPa or less, a reinforcement layer 12 provided on an outer peripheral surface of the inner layer 11, and an outer layer 13 provided on the outside of the reinforcement layer 12 and made of a polyester resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brake hose for transmitting hydraulic pressure in a hydraulic brake system.

  2. Description of the Related Art Conventionally, a hydraulic brake system that activates a brake by applying pressure to the brake fluid is often used in a vehicle such as an automobile. Transmission of hydraulic pressure to the brake is generally performed via a flexible brake hose as described in Patent Documents 1 and 2, for example. Such a brake hose is generally composed of at least three layers (an inner layer, a reinforcing layer, and an outer layer). If each layer is easily expanded, the hydraulic pressure is quickly transmitted to the brake. Therefore, the response of the brake is deteriorated. Therefore, it is important to improve the low expansion of the brake hose.

  The brake hose of Patent Document 1 is configured by providing an inner layer rubber, a first reinforcing fiber layer, an intermediate rubber, a second reinforcing fiber layer, and an outer layer rubber in this order from the inside. And it is supposed that the low expansion | swellability of a brake hose can be ensured by employ | adopting a polyethylene-2, 6-naphthalate fiber for a 2nd reinforcement fiber layer.

  Further, the brake hose of Patent Document 2 is configured by laminating an inner surface material layer, a first reinforcing layer, an intermediate material layer, a second reinforcing layer, and an outer surface covering layer. In this brake hose, the amount of expansion of the hose during pressurization is reduced by defining the reinforcing yarn used for the reinforcing layer to have a dry heat shrinkage of 1% or more at the vulcanization temperature.

JP 2001-21068 A Japanese Patent Laid-Open No. 2003-74760

  By the way, in a product such as a mountain bike or a road bike, where the demand for brake response is stricter than that of a general brake, it is necessary to sufficiently ensure the low expansion of the brake hose. The brake hoses described in Patent Documents 1 and 2 are intended to reduce the expansion of the brake hose by defining the material of the reinforcing layer, but the inner layer and the outer layer constituting the main part of the brake hose are made of rubber in the first place. For this reason, there is a limit to low expansibility, and it has not been able to meet the strict requirements for brake response.

  Therefore, it is conceivable to use a resin material or the like that is less elastically deformed than rubber as a material for the brake hose and to reduce the expansion of the brake hose. However, if a material that is not easily elastically deformed is used, the bending durability generally decreases, and a problem that sufficient bending durability cannot be obtained particularly in a low temperature environment may occur. If it does so, it could endure the use environment at the time of a real vehicle run, and there was a possibility that a brake hose might be damaged.

  Accordingly, an object of the present invention is to provide a brake hose that achieves both low expansibility and low-temperature bending durability.

  The brake hose according to the present invention includes an inner layer made of an aromatic polyamide resin having a flexural modulus of 1400 MPa or more and 2000 MPa or less, a reinforcing layer provided on the outer peripheral surface of the inner layer, a polyester-based resin provided outside the reinforcing layer, And an outer layer.

  The brake hose according to the present invention employs an aromatic polyamide resin for the inner layer and a polyester resin for the outer layer. Since the aromatic polyamide resin is excellent in low-temperature characteristics, the use of the aromatic polyamide resin for the inner layer can improve the low-temperature bending durability of the brake hose. On the other hand, the aromatic polyamide resin generally has a low flexural modulus and is slightly inferior in low expansibility as compared with the polyester resin used for the outer layer. However, in the present invention, the lower limit of the flexural modulus of the aromatic polyamide resin used for the inner layer is regulated to 1400 MPa, thereby suppressing the expansion of the inner layer and ensuring the low expansion of the brake hose. In addition, since the reinforcing layer is directly provided on the outer peripheral surface of the inner layer, expansion of the inner layer is surely suppressed by the reinforcing layer, and further expansion of the brake hose is possible. As described above, according to the present invention, it is possible to provide a brake hose having both low expansibility and low temperature bending durability.

  Here, it is preferable that the reinforcing layer is formed by braiding reinforcing yarn made of polyvinyl alcohol fiber. In this way, by forming the reinforcing layer by braiding the reinforcing yarn, the strength of the reinforcing layer is improved, and the expansion of the inner layer can be more reliably suppressed. Further, by using a polyvinyl alcohol fiber as the reinforcing yarn, for example, the expansion of the brake hose can be reduced while suppressing the thickness of the reinforcing layer as compared with the case where the reinforcing yarn is formed of metal.

1 is a partially cutaway perspective view showing an embodiment of a brake hose according to the present invention. It is a schematic diagram for demonstrating a low-temperature bending endurance test.

  An embodiment of a brake hose according to the present invention will be described. FIG. 1 is a partially cutaway perspective view of a brake hose 1 in the present embodiment. The brake hose 1 is a flexible hose having a three-layer structure in which an inner layer 11, a reinforcing layer 12, and an outer layer 13 are laminated in order from the radially inner side. The internal space of the inner layer 11 is filled with an internal fluid such as a brake fluid, and a brake (not shown) is activated when pressure acts on the internal fluid. The vehicle on which the brake hose 1 is mounted is not particularly limited, but it can be suitably used in a mountain bike for competitions, in particular, where the demand for brake response is strict and the low temperature bending durability of the brake hose is also required. .

  The inner layer 11 is made of an aromatic polyamide resin. The aromatic polyamide resin is excellent in low-temperature characteristics, and by using this for the inner layer 11, the low-temperature bending durability of the brake hose 1 can be improved. In the brake hose 1, the flexural modulus of the aromatic polyamide resin forming the inner layer 11 is 1400 MPa or more. As described above, the lower limit of the flexural modulus is defined and the expansion of the inner layer 11 is suppressed, so that the low expansion property of the brake hose 1 is ensured.

  As an aromatic polyamide resin having a flexural modulus of 1400 MPa or more, for example, PA10T (polyamide 10T) can be employed. However, the aromatic polyamide resin used for the inner layer 11 is not limited to PA10T. If the flexural modulus is 1400 MPa or more, PA8T, PA12T can obtain high crystallinity as with other materials, for example, PA10T. It is also possible to adopt.

  A reinforcing layer 12 is provided on the outer peripheral surface of the inner layer 11. Thus, by providing the reinforcing layer 12 directly on the outer peripheral surface of the inner layer 11, the expansion of the inner layer 11 can be reliably suppressed by the reinforcing layer 12. The reinforcing layer 12 is configured by braiding fibrous reinforcing yarns on the inner layer 11. With this configuration, the strength of the reinforcing layer 12 is improved, and expansion of the inner layer 11 can be more reliably suppressed.

  Here, various fibers such as metal fibers, polyvinyl alcohol fibers, polyester fibers, and polyamide fibers can be used for the reinforcing yarn. However, when metal fibers are used, the reinforcing layer 12 becomes thick and the brake hose 1 may have a large diameter. Therefore, in order to realize a low expansion of the brake hose 1 while suppressing the thickness of the reinforcing layer 12, it is preferable to use resin fibers such as polyvinyl alcohol fibers, polyester fibers, and polyamide fibers. Furthermore, in view of cost performance, it is preferable to use a polyvinyl alcohol fiber having a higher modulus.

  Further, by braiding the reinforcing yarn in a state where a tensile stress is applied, the reinforcing layer 12 can be formed so as to tighten the inner layer 11, and the expansion of the inner layer 11 can be further suppressed. As a braiding method, it is preferable to employ blade knitting having excellent strength.

  Further, an outer layer 13 made of a polyester resin is provided on the outer peripheral surface of the reinforcing layer 12. Thus, by providing the outer layer 13 directly on the outer peripheral surface of the reinforcing layer 12 while the outer layer 13 is made of a polyester-based resin, the low expansion of the reinforcing layer 12 and the outer layer 13 can be improved, and the brake hose 1 as a whole As a result, the expansion can be further reduced.

  As the material of the outer layer 13, among polyester-based resins, it is possible to reduce costs by adopting a polyethylene terephthalate (PET) resin or a polybutylene naphthalate (PBN) resin. However, other polyester resins can be used.

  As described above, the brake hose 1 employs an aromatic polyamide resin for the inner layer 11 and a polyester resin for the outer layer 13. Since the aromatic polyamide resin is excellent in low temperature characteristics, the low temperature bending durability of the brake hose 1 can be improved by using the aromatic polyamide resin for the inner layer 11. On the other hand, the aromatic polyamide resin generally has a small flexural modulus and is slightly inferior in low expansibility as compared with the polyester resin used for the outer layer 13. However, in the brake hose 1, the lower limit value of the flexural modulus of the aromatic polyamide resin used for the inner layer 11 is regulated to 1400 MPa, thereby suppressing the expansion of the inner layer 11 and ensuring the low expansibility of the brake hose 1. Yes. In addition, since the reinforcing layer 12 is directly provided on the outer peripheral surface of the inner layer 11, the expansion of the inner layer 11 is surely suppressed by the reinforcing layer 12, and the brake hose 1 can be further reduced in expansion. Therefore, the brake hose 1 can be made to have both low expansibility and low-temperature bending durability, and the demand for the response of the brake is strict, and the low-temperature bending durability of the brake hose is also required. It can withstand use.

  In the present embodiment, the brake hose 1 has a three-layer structure including the inner layer 11, the reinforcing layer 12, and the outer layer 13. However, the brake hose 1 may have a structure of four or more layers. However, by realizing a low expansion with the brake hose 1 having a three-layer structure as in the present embodiment, the diameter of the brake hose 1 can be suppressed, and the brake hose 1 can be easily handled. it can.

[Verification test]
In order to verify the low expansibility of the brake hose 1, an expansion amount test of the brake hose 1 was performed. In Examples 1 and 2 and Comparative Examples 1 and 2, the brake hose 1 has a three-layer structure including an inner layer 11 made of PA10T, a reinforcing layer 12 made of polyvinyl alcohol fiber, and an outer layer 13 made of PET resin. In addition, the flexural modulus of PA10T constituting the inner layer 11 was 1400 to 1500 MPa in Example 1, 1900 to 2000 MPa in Example 2, 800 to 900 MPa in Comparative Example 1, and 2400 to 2500 MPa in Comparative Example 2. Test results regarding Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1 together with Examples (Comparative Examples 3 to 5) described in Patent Documents 1 and 2 described above. For details of the test, see [0024], [0031], [0032], and [FIG. 3] of Patent Document 2.

  As is clear from Table 1, in any of the test pressures of 6.86 MPa and 10.3 MPa, in Examples 1 and 2 and Comparative Examples 1 and 2, the amount of expansion was significantly larger than that of Comparative Examples 3 to 5. Is getting smaller. In Comparative Examples 3 to 5, the material constituting the reinforcing layer is used to reduce the expansion of the brake hose, but the inner layer and the outer layer, which are the main parts, are made of rubber. On the other hand, in Examples 1 and 2 and Comparative Examples 1 and 2, the inner layer 11 which is the main part of the brake hose 1 is made of a polyamide-based resin and the outer layer 13 is made of a polyester-based resin. It is thought that we were able to plan. In particular, in Examples 1 and 2 and Comparative Example 2 (shown by a thick frame in Table 1) in which the flexural modulus of the polyamide-based resin constituting the inner layer 11 is 1400 MPa or more, a result satisfying the target value was obtained. .

  Furthermore, the test for verifying the low temperature bending durability regarding Examples 1 and 2 and Comparative Examples 1 and 2 of the brake hose 1 was performed. FIG. 2 is a schematic diagram for explaining a low-temperature bending durability test. As shown in FIG. 2, this low-temperature bending durability test is performed using a brake hose assembly 10 in which both ends of the brake hose 1 are attached to a test apparatus via a fitting 11.

  First, as shown in FIG. 2b, the brake hose assembly 10 is attached to a test apparatus so that the minimum bending radius when bent is 20 mm, and the ambient temperature is adjusted to −30 ° C. ± 2 ° C. Next, a predetermined brake fluid (for example, one specified in JIS-K2233) is sealed in the brake hose assembly 10 so that the fluid pressure is 4.9 MPa. Then, a test was conducted 500,000 times with a bending stroke of 150 mm and a bending cycle of 150 cpm (2.5 Hz) so that the state of FIG. I confirmed that there was no.

  When such a low-temperature bending durability test was conducted for Examples 1 and 2 and Comparative Examples 1 and 2, Examples 1 and 2 and Comparative Example 1 in which the flexural modulus of the polyamide-based resin constituting the inner layer 11 was 2000 MPa or less. In either case, no damage or abnormality was observed even after repeating the target bending of 500,000 times, and it was verified that the brake hose 1 has sufficient low-temperature bending durability. On the other hand, in Comparative Example 2 in which the flexural modulus of the polyamide resin constituting the inner layer 11 is 2400 to 2500 MPa, the inner layer 11 was damaged when it was bent about 210,000 times.

  From the above test results, it was shown that both the low expansion of the brake hose 1 and the low temperature bending durability can be ensured by setting the flexural modulus of the polyamide resin constituting the inner layer 11 to 1400 MPa or more and 2000 MPa or less. .

1 Brake hose 11 Inner layer 12 Reinforcement layer 13 Outer layer

Claims (2)

An inner layer made of an aromatic polyamide resin having a flexural modulus of 1400 MPa to 2000 MPa,
A reinforcing layer provided on the outer peripheral surface of the inner layer;
An outer layer provided on the outside of the reinforcing layer and made of a polyester-based resin;
A brake hose comprising:   The brake hose according to claim 1, wherein the reinforcing layer is formed by braiding reinforcing yarn made of polyvinyl alcohol fiber.

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