Brake hose

Details Brake hose Brake hose

2002-11-25

2003-09-30

Brinson, Patrick (Department: 3752)

Pipes and tubular conduits

Flexible

Braided, interlaced, knitted or woven

C138S137000, C138S140000

Reexamination Certificate

active

06626211

ABSTRACT:

This application claims the benefit of and priority from Japanese Applications No. 2001-360375 filed Nov. 27, 2001 and No. 2001-360379 filed Nov. 27, 2001, the content of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a brake hose having two reinforcing yarn layers including a lower yarn layer and an upper yarn layer in a rubber base.
2. Description of the Related Art
A brake hose known in the conventional art is shown in
FIG. 16
(JP 06-201076A).
FIG. 16
is a cross-section of the main components of a conventional brake hose
200
. Because the brake hose
200
must have high resistance against brake fluid pressure, it is formed from several layers of rubber and fiber yarn. The brake hose
200
comprises an inner tube rubber layer
202
, a lower yarn layer
204
, an intermediate rubber layer
206
, an outer yarn layer
208
, and a cover rubber layer
210
.
The brake hose
200
is required to meet a higher pressure resistance standard than a coolant system hose or a fuel system hose. As fluid temperatures and pressure levels of automobile system have increased in recent years, the demand for higher pressure resistance has increased as well.
The pressure from the pressure fluid flowing in the flow path
201
inside the brake hose
200
is transmitted from the inner circumference area of the brake hose
200
to the outer circumference area thereof. In other words, the pressure is transmitted to the inner tube rubber layer
202
, the lower yarn layer
204
, the intermediate rubber layer
206
, the upper yarn layer
208
and the cover rubber layer
210
, causing each layer to expand. Each layer has a binding force that operates against the pressure exerted by the pressure fluid and inhibits expansion of such layer. The inner tube rubber layer
202
, the intermediate rubber layer
206
and the cover rubber layer
210
are highly elastic, and are responsible for no more than 10% of the total binding force, while the majority of the binding force is possessed by the lower yarn layer
204
and the upper yarn layer
208
. Consequently, increasing the binding force of the lower yarn layer
204
and the upper yarn layer
208
increases the durability and expansion resistance (i.e., resistance to cubical expansion) provided by the brake hose
200
. As a result, increasing both of these characteristics by changing the type of yarn material used and the braiding method of the yarn layers has been examined.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a brake hose that offers increased durability and expansion resistance.
In accordance with one embodiment of the present invention, a brake hose includes two reinforcing layers in a rubber base. The brake hose comprises an inner tube rubber layer having a flow path for flowing fluid, a lower yarn layer formed by braiding first yarns around the inner tube rubber layer and an upper yarn layer formed by braiding second yarns around the lower yarn layer and a cover rubber layer covering the upper yarn layer. A lower yarn layer duty LD given by the equation, LD(%)=(LRP/PRP)×100, has a value of 50-65%, LRP denotes an inner pressure at which a brake hose without the upper yarn layer and the cover would burst, and PRP denotes an inner pressure at which the brake hose would burst.
In the brake hose pertaining to the present invention, the pressure exerted by the pressure fluid flowing in the flow path is transmitted from the inner circumference area of the brake hose to the outer circumference area thereof, i.e., from the interior of the rubber base to the lower yarn layer and the upper yarn layer, causing each such layer to expand. A binding force that restricts the expansion of the brake hose in resistance to the pressure from the pressure fluid is generated. The rubber base is responsible for no more than 10% of the total binding force due to its high elasticity, while the majority of the binding force is exerted by the lower yarn layer and the upper yarn layer.
Because the fluid pressure transmitted in this fashion travels from the inner circumference area to the outer circumference area of the brake hose in a radial fashion, the fluid pressure diminishes per unit area as it travels to the outer circumference area, and the lower yarn layer in the inner circumference area of the brake hose receives a larger amount of expansion force than the upper yarn layer. As a result, where the lower yarn layer and the upper yarn layer are formed from yarn made of the same material, the yarn of the lower yarn layer receives a greater tensile force than the yarn of the upper yarn layer. This means that even where the first yarns bursts after receiving a large amount of tensile force, there is still some degree of margin or leeway before the second yarns bursts. In view of this fact, the percentage burden assumed by the lower yarn layer is set at 50-65% of the total burden. In other words, the percentage burden assumed by the second yarns is set to a value larger than in a conventional brake hose, while the burden assumed by the first yarns is reduced. Consequently, the burden on each individual strand of yarn becomes smaller, and the ultimate rupturing pressure that may be applied to the brake hose can be increased.
The percentage burden assumed by the lower yarn layer is set to 50-65% because the first yarns and second yarns must satisfy prescribed levels of tensile strength and elongation. Therefore, a material such as vinylon, polyethylene terephthalate, polyethylene naphthalate or rayon is used, for example, because it would be difficult as a practical matter to set the percentage burden to be assumed by the lower yarn layer at less than 50% using these yarns, while if the lower yarn layer percentage burden were to exceed 65%, the higher rupturing pressure that comprises one characteristic of the present invention could not be obtained.
It is preferred that the second yarns of the upper yarn layer has a lower elongation than the first yarns of the lower yarn layer. Because the upper layer yarn is less subject to elongation when subjected to tensile force, it can handle a large amount of force up to the point at which the lower yarn layer expands and bursts.
For example, yarn having a tensile strength of 8.5 g per decitex and a elongation of 3.0±1% at a tensile load of 2.7 g can be used for the second yarns, and yarn having a tensile strength of 6.5 g per decitex and a elongation of 3.5±1% at a tensile load of 2.7 g can be used for the first yarns. A decitex is a unit of measurement that expresses the weight(
2
) of a fiber relative to its length, and is equal to one gram per 10,000 meters of yarn.
The brake hose according to another aspect of the present invention comprises an inner tube rubber layer that has a flow path in which a pressure fluid flows and is formed from a rubber material, a lower yarn layer formed via braiding of first yarns around this inner tube rubber layer, an upper yarn layer that is formed via braiding of second yarns around this lower yarn layer, and a cover rubber layer that is formed around this upper yarn layer. The lower yarn layer is formed from first yarns strands that have on the surface thereof an adhesive thin film formed via RFL processing and a rubber thin film composed of EPDM that adheres to the adhesive thin film and the inner tube rubber layer, such layers formed in a sequential order. EPDM refers to ethylene-a-olefin-unconjugated diene copolymer (propylene as a-olefin).
The above-mentioned first yarns comprises a filament bundle composed of bundled filament threads, on each of which is formed an undercoat layer using an epoxy primer process. The above-mentioned adhesive thin film and rubber thin film are sequentially applied to the outer surface of each filament bundle.
The above-mentioned first yarns comprises a filament bundle composed of bundled filament threads. An undercoat is formed on the outer surface of each filament bundle using an epoxy primer process, and an adhesive

Affiliated with

Also associated with

Rating

Brake hose does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Brake hose, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brake hose will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3081643