Advanced brake hose

Abstract

The invention relates to a brake hose (1) comprising, from the inside out, at least an inner rubber sheath (2), a first textile braid (3), and an outer rubber sheath (4). According to the invention, the hose includes a barrier film (5) positioned between the inner sheath (2) and the outer sheath (4) to prevent the rubber from flowing back up through the first textile braid (3). Figure for the abstract: Fig. 1

Description

Title of the invention: Improved brake hose technical field

[0001] The present invention relates to the field of brake pipes, particularly automotive. Previous art

[0002] A conventional brake hose generally consists, from the inside out, of an inner EPDM sheath, a first textile braid, a bonding layer, a second textile braid and an outer EPDM sheath.

[0003] The assembly is then vulcanized to give the mechanical characteristics to the different rubbers and to bond the layers together.

[0004] Brake hose manufacturers seek strong adhesion between layers to ensure a high-performance brake hose, minimal water permeability to protect the brake fluid and maintain braking performance, and a hose without external defects (bubbles, bumps, holes) that could compromise the crimping of the metal ends and indicate a lack of control over the manufacturing process, resulting in a lower quality product.

[0005] However, during the vulcanization of the brake pipe, the temperatures and cooking times required (approximately 150°C for 90 minutes) cause a more or less significant shrinkage of the textile fibers (PVA or PET or Aramid).

[0006] This shrinkage occurs before the EPDM is fully vulcanized, sometimes resulting in the EPDM migrating upwards through the textile braid fibers. This EPDM migration, known as skirt migration, manifests as bump-like defects on the outer sheath of the finished pipe.

[0007] To ensure adhesion of the fibers to the EPDM, specialists use pre-treated fibers, with adhesion to the rubber occurring during vulcanization. To create adhesion between the textile braids, they either apply an adhesive between the fibers or use a thin strip of unvulcanized EPDM placed between the two braids.

[0008] The liquid adhesives used are solvent-based or water-based. In the former case, specific equipment is required. The use of liquid-based adhesives generally necessitates complex industrial processes (application, drying, effluent and waste treatment). In the case of EPDM strips, competitive suppliers must be found and the strip vulcanized, which is generally a costly solution.

[0009] Vulcanized EPDM is not completely waterproof. However, one of the criteria sought by automotive manufacturers is to protect the brake fluid inside the hose from moisture and water potentially present in the brake environment. To overcome this constraint, specialists use a thick layer of rubber to slow water penetration into the hose, which increases the hose's production costs and its environmental impact. The use of hydrophilic fibers (PVA) also appears to play an important role.

[0010] To prevent skirt lift, specialists either pre-vulcanize the inner rubber sheath before braiding the textile fibers, or maintain a sufficient fiber density in the first and second braids. Pre-vulcanization complicates, or even slows down, the extrusion process of the inner rubber sheath. In the latter case, the increased fiber density raises the cost of the hose. Description of the invention

[0011] One of the aims of the present invention is therefore to overcome the disadvantages of the prior art by proposing a brake pipe that makes it possible to avoid skirt-up problems in a simple, inexpensive and rational way.

[0012] Another objective of the invention is to provide such a pipe which ensures water impermeability to protect the brake fluid.

[0013] Another objective is to provide such a pipe whose weight is not increased so as not to increase its environmental impact.

[0014] For this purpose, a brake hose has been developed comprising at least, from the inside out, an inner rubber sheath, a first textile braid, and an outer rubber sheath.

[0015] According to the invention, the brake hose includes a barrier film, preferably with a thickness between 20 and 150 sqm, positioned between the inner sheath and the outer sheath in order to prevent the rubber from rising through the first textile braid.

[0016] In this way, the invention makes it possible to prevent problems of rubber rising through the textile braid, and therefore of defects on the outer sheath, in a simple and rational way, but also to improve the water permeability performance of brake hoses by blocking the penetration of water through the rubber.

[0017] The proposed solution does not increase the cost of the process, nor the weight of the pipe, so the environmental impact is not increased.

[0018] According to a particular embodiment, the brake hose comprises a second textile braid, positioned between the first textile braid and the outer sheath, in order to, to improve the performance of the brake hose, particularly in terms of pressure resistance.

[0019] From the above, several forms of embodiment can be envisaged.

[0020] For example, the film can be positioned between the inner sheath and the first textile braid, or between the first textile braid and the second textile braid, or between the second textile braid and the outer sheath.

[0021] According to a particular embodiment, the film is multilayered with at least one central layer whose melting temperature is higher than the vulcanization temperature, for example higher than 170°C and two outer layers whose melting temperature is lower than the vulcanization temperature, for example lower than 145°C.

[0022] This configuration is independent of the film's position within the hose, but offers a particular advantage when the hose comprises two textile braids and the film is positioned between these two braids, since the melting of the outer layers during the vulcanization of the brake hose ensures adhesion between the two textile braids. The central layer, on the other hand, does not melt during vulcanization and retains a certain tenacity that prevents the rubber from migrating between the fibers of the textile braids.

[0023] According to particular embodiments, the central layer is made of polyamide or polyethylene terephthalate or polypropylene, and the outer layers are made of polyethylene or polypropylene.

[0024] The multilayer film may also include two intermediate layers positioned between the central layer and the external layers, for example made of polyethylene, polypropylene, polyethylene terephthalate, in order to increase the strength and performance of the brake pipe. Brief description of the drawings

[0025] [Fig. 1] is a schematic longitudinal sectional representation of a brake pipe according to the invention.

[0026] [Fig.2] is a schematic cross-sectional representation of a first embodiment of a barrier film implemented in the invention.

[0027] [Fig.3] is a schematic cross-sectional representation of a second embodiment of a barrier film implemented in the invention. Detailed description of the invention

[0028] With reference to Figures 1 to 3, the present invention relates to an innovative brake hose (1) designed to improve the performance and durability of vehicle braking systems. This brake hose (1) comprises several layers arranged in a specific way to optimize its mechanical and water resistance properties.

[0029] The brake hose (1) comprises, from the inside out, an inner rubber sheath (2), for example made of EPDM, called a skirt and intended to contain the brake fluid. Around this inner sheath (2) is a first textile braid (3), composed for example of yarns made of Polyethylene Terephthalate (PET) or Polyvinyl Alcohol (PVA), or Aramid, which provides a reinforcing structure for the mechanical strength of the hose.

[0030] An outer EPDM sheath (4) surrounds the structure, providing additional protection against external elements and increased wear resistance. The distinctive feature of this brake hose (1) is the arrangement of a barrier film (5) positioned between the inner sheath (2) and the outer sheath (4). This film (5) is shaped like a sleeve and surrounds the inner sheath (2). This barrier film (5) prevents the rubber of the inner sheath (2) from wicking up through the first textile braid (3), known as skirt wicking, thus preventing defects such as bumps on the outer surface of the finished hose.

[0031] The brake hose (1) may include, in this order, optionally a bonding layer, such as a liquid adhesive or a rubber strip with a thickness of 20 to 40 µm, and a second textile braid (6), also, for example, composed of PET, PVA, or Aramid yarns, positioned between the first textile braid (3) and the outer sheath (4). This configuration further reinforces the overall structure of the hose.

[0032] Under these conditions, the barrier film (5) is preferably positioned between the first textile braid (3) and the second textile braid (6). This film (5) is advantageously of the multilayer type, with at least one central layer (5a) whose melting temperature is greater than 170°C and two external layers (5b) whose melting temperature is less than 145°C, thus allowing adhesion between the first textile braid (3) and the second textile braid (6), and thus eliminating the need for a bonding layer.

[0033] The central layer (5a) of the multilayer film (5) is preferably made of polyamide, polyethylene terephthalate, or polypropylene, while the outer layers (5b) are made of polyethylene or polypropylene. This combination of materials ensures good thermal resistance and excellent compatibility with the surrounding textile fibers.

[0034] In addition, the multilayer film (5) may include two intermediate layers (5c), for example made of polyethylene or polypropylene, positioned between the central layer (5a) and the outer layers (5b), thus adding additional barrier properties and improving the overall cohesion of the film (5).

[0035] Finally, the barrier film (5) has a thickness between 20 and 150 pm, which makes it possible to balance the protection offered and the flexibility required for application in braking systems.

[0036] This innovation in brake pipe design makes it possible to obtain high-performance, lightweight products and therefore with a limited environmental impact, while exhibiting excellent adhesion between layers, increased water impermeability, and resistance to surface defects, thus meeting the rigorous requirements of automotive manufacturers.

Claims

Demands

1. Brake hose (1) comprising at least, from the inside out, an inner rubber sheath (2), a first textile braid (3), an outer rubber sheath (4), characterized in that it comprises a barrier film (5) positioned between the inner sheath (2) and the outer sheath (4) in order to prevent the rubber from rising through the first textile braid (3).

2. Brake hose (1) according to claim 1, characterized in that it comprises a second textile braid (6) positioned between the first textile braid (3) and the outer sheath (4).

3. Brake hose (1) according to claim 2, characterized in that the film (5) is positioned between the first textile braid (3) and the second textile braid (6).

4. Brake pipe (1) according to claim 3, characterized in that the film (5) is multilayer with at least one central layer (5a) whose melting temperature is greater than 170°C and two external layers (5b) whose melting temperature is less than 145°C to make the adhesion between the first textile braid (3) and the second textile braid (6).

5. Brake pipe (1) according to claim 4, characterized in that the central layer (5a) is made of polyamide or polyethylene terephthalate or polypropylene, and the outer layers (5b) are made of polyethylene or polypropylene.

6. Brake pipe (1) according to any one of claims 4 to 5, characterized in that the multilayer film (5) comprises two intermediate layers (5c) positioned between the central layer (5a) and the outer layers (5b).

7. Brake pipe (1) according to any one of the preceding claims, characterized in that the film (5) has a thickness between 20 and 150 pm.

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