JP2748223B2 - Durable brake hose and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a durable brake hose used for an automobile brake device and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a hydraulic brake of an automobile, a stepping force of a brake pedal is changed to a hydraulic pressure by a master cylinder and transmitted to each wheel cylinder through a brake hose. Conventional brake hoses consist of a rubber tube and a braided reinforcing layer. FIG. 3 is a perspective view in which a part of the brake hose is cut away, and FIG. 4 is a partially enlarged sectional view. Brake hoses are made of oil-resistant ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SB
R) or the like, a first reinforcing layer 11 formed by braiding vinylon yarn as a reinforcing yarn, natural rubber (NR), EP
DM) an intermediate rubber layer 12 of butyl rubber (IIR) or the like;
A second reinforcing layer 13 formed by braiding vinylon yarn, and E
Outer rubber tube 14 made of PDM and chloroprene rubber (CR)
It is composed of

[0003] The brake hose having the above structure is usually manufactured as follows. That is, the inner rubber tube 10 is extruded around the outer periphery of a long resin mandrel prepared in advance, and the first reinforcing layer 11 is braided on the outer surface of the inner rubber tube 10.
Next, the intermediate rubber layer 12 is formed by extruding the outer peripheral surface of the first reinforcing layer 11 with an extruder or by winding a long rubber tape. When the rubber tape is wound, the second reinforcing layer 13 is braided while the rubber tape is wound. . Further, an outer rubber tube 14 is extruded around the outer periphery of the second reinforcing layer 13. These rubber hoses are vulcanized together with a long mandrel, and after vulcanization, the long mandrel is pulled out using water pressure, and the long rubber hose is thereafter cut into a predetermined length for use.

[0004]

However, the conventional brake hose and its manufacturing method have the following problems. The brake hose is continually rocked by repeated pressurization due to the depressing force of a brake pedal and tire bounce and rebound during running. For this reason, the yarns forming the reinforcing layers 11 and 13 are rubbed by repeated pressurization and swinging, and abrasion of the yarn occurs. In the brake hose,
The failure mode is such that the reinforcing layer is not stopped by the internal pressure and bursts due to the abrasion of the yarn. Conventional brake hoses
Intermediate rubber layer 1 between first reinforcing layer 11 and second reinforcing layer 13
2, the intermediate rubber layer 12 is not embedded between the stitches and the overlapping yarns in the reinforcing layer. This is because a high-pressure hose such as a brake hose has a tightly braided reinforcing yarn. Therefore, the intermediate rubber layer 12
Is effective in preventing the wear between the first reinforcing layer 11 and the second reinforcing layer 13 but is not effective in preventing the yarns in the reinforcing layer from being worn.

If the rubber used for the intermediate rubber layer 12 is a rubber material having a lower permeability to brake fluid than the rubber for the inner rubber tube 10, the brake fluid transmitted from the inner rubber tube 10 is suppressed by the intermediate rubber layer 12. Would be done. The suppressed brake fluid permeates the first reinforcing layer 11 as it is, promoting the deterioration of the yarn and causing a decrease in the durability of the hose. In the case where the intermediate rubber layer 12 is formed by extrusion, process control such as adjustment of extrusion speed and wall thickness is required. In the case where the intermediate rubber layer 12 is formed by winding a rubber tape, the intermediate reinforcing layer 13 is wound when the second reinforcing layer 13 is braided. And it was difficult to wind it evenly.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a brake hose having excellent durability under repeated pressure swings.

[0007]

The present invention has the following configuration to achieve the above object. That is, a durable brake hose according to the present invention is a brake hose having two braided reinforcing layers of reinforcing yarn between an inner rubber pipe and an outer rubber pipe. And a filling rubber layer covering the outer peripheral surface of the reinforcing yarn is provided, and the rubber of the filling rubber layer is made of rubber having better permeability of brake fluid than the rubber of the inner rubber tube. The filled rubber layer can be formed by applying a rubber paste and forcibly embedding the stitches. Preferably, the inner rubber tube and the outer rubber tube are formed of EPDM, the reinforcing layer is braided with vinylon yarn, and the rubber for preparing the rubber paste is CR.

In the method of manufacturing a brake hose having the above structure, an inner rubber tube is extruded on the outer peripheral surface of a long mandrel, and then a first reinforcing layer of braided vinylon yarn is provided on the outer peripheral surface of the inner rubber tube. . Next, while transferring the hose provided with the first reinforcing layer, the rubber has a viscosity of 200 to 1000 poise, is dipped in a rubber paste tank prepared by CR, and is applied. The rubber glue is forcibly embedded in the stitches by passing through a rubber ring having a diameter smaller than the diameter. Thereafter, a second reinforcing layer made of a braided vinylon yarn is provided, and finally, the outer rubber tube is extruded by EPDM. Rubber viscosity of rubber paste is 200
The reason for setting the polish to 1000 poise is that when the polish is 200 poise or less, the rubber paste permeates the yarn and does not remain on the stitches, and also penetrates to the second reinforcing layer to reduce the adhesive force with the outer rubber tube. Further, if the rubber viscosity of the rubber paste is 1000 poise or more, the viscosity is too high and the rubber paste does not flow to the lower side of the hose, and as a result, cavitation (cavity) occurs on the lower side of the hose, and the rubber paste Is not applied.

[0009]

The rubber paste forcibly embedded in the stitches of the reinforcing layer forms a filled rubber layer, thereby preventing the yarns from directly rubbing each other. Further, the rubber paste is prepared by CR having a higher permeability of the brake fluid than the inner rubber tube, and does not form the intermediate rubber layer as in the related art, so that the penetration of the brake fluid into the yarn is prevented. At the exit of the rubber glue tank, a rubber ring is used, so that the rubber glue is forcibly embedded in the stitches.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described.
First, an enlarged cross section of a brake hose according to the present invention is shown in FIG.
Shown in In the figure, reference numeral 20 denotes E where the brake fluid hardly permeates.
An inner rubber tube made of PDM, 21 is a first reinforcing layer braided with vinylon yarn on the outer peripheral surface of the inner rubber tube 20, and 22 is filled with rubber paste to embed between stitches to cover the outer peripheral surface of vinylon yarn. 23 is a second reinforcing layer formed by braiding the outer peripheral surface of the filled rubber layer 22 with vinylon yarn, and 24 is an outer rubber tube coated with EPDM. The rubber glue forming the filled rubber layer 22 is more excellent in brake fluid permeability than the EPDM forming the inner rubber tube 20, and was prepared with a polar CR.

In the above embodiment, the filled rubber layer 22 is provided only on the first reinforcing layer 21, but may be provided on the second reinforcing layer 23 as well. The pressure resistance of the brake hose is maintained by the first reinforcement layer 21 and the second reinforcement layer 23 merely performs an auxiliary function.
1 is sufficient.

[0012] The method of manufacturing the brake hose having the above structure is as follows.
This is basically the same as the conventional manufacturing method in that the inner rubber tube 20 is extruded on a long mandrel, the first and second reinforcing layers are provided by braiding, and finally the outer rubber tube is extruded.
The difference from the conventional manufacturing method is that, after the braiding step of the first reinforcing layer, a step of applying a rubber paste in place of the extrusion molding of the intermediate rubber layer and forcibly embedding the stitches to form a filled rubber layer is provided. The point is that the step of extruding the intermediate rubber layer is omitted. FIG. 2 shows a method of applying rubber paste using a rubber paste tank. In the rubber glue tank 25, through holes 26 and 27 having a diameter larger than the braid diameter of the first reinforcing layer 21 are formed on opposing side surfaces of the lower end, and the through holes 26 and 27 are formed in the through holes 26 and 27. Each rubber ring 2
8, 29 are fixed on the same axis.

The rubber rings 28 and 29 have a rubber hardness Hs.
40 to 70, the insertion holes 30 and 31 through which the hose is inserted.
Is formed 0.1 to 0.3 mm smaller than the braid diameter of the first reinforcing layer. Rubber rings 28 and 29 have rubber hardness Hs
If it is less than 40, the hose is inferior in wear resistance and is worn while the hose is being transferred, and the ironing for forcibly embedding the rubber glue into the stitch becomes insufficient. Accordingly, more rubber glue is applied to the first reinforcing layer 21 than necessary. On the other hand, if the rubber hardness Hs is 70 or more, it lacks flexibility and the ironing effect is too large to cover the rubber paste uniformly. A funnel-shaped notch 32 is formed on the outer surface of the rubber ring 28 to facilitate insertion of the hose, and a funnel-shaped notch 33 is formed on the inner surface of the rubber ring 29 to enhance the ironing effect. .

The rubber paste 34 in the rubber paste tank 25 is adjusted to a viscosity of 200 to 1000 poise by CR. If the viscosity of the rubber glue is 200 poise or less, the rubber glue permeates the yarn and does not remain on the stitch, but also the second reinforcing layer 2
3 to reduce the adhesive strength between the outer rubber tube 24 and the second reinforcing layer 23. The viscosity of the rubber paste is 10
Above 00 poise, cavitation (cavity) occurs on the lower side of the hose because the flow of the rubber adhesive on the upper side of the hose is small when the hose is transferred through the rubber adhesive and the hose is not caught on the lower side of the hose. As a result, rubber glue is not applied to the entire circumference of the hose.

To apply rubber glue to the outer peripheral surface of the first reinforcing layer 21, a hose is inserted from the rubber ring 28 side, pulled out from the rubber ring 29 on the opposite side, and transferred at a constant speed while immersing in the rubber glue tank 25. do it. Since the rubber glue attached to the outer peripheral surface of the first reinforcing layer 21 is wrung by the rubber ring 29, it is forcibly embedded in the stitches and covers the outer peripheral surface.

Next, test results of the brake hose according to the present invention will be described. First, the application state of the rubber paste on the first reinforcing layer 21 and the embedding state in the stitch due to the difference in viscosity of the rubber paste were examined. When the rubber glue is completely applied to the outer peripheral surface of the first reinforcing layer 21 and the rubber glue is completely embedded in the stitches, a mark "○" indicates that the rubber glue is not completely applied or the rubber glue is applied to the stitches. The case where the embedding was not complete was evaluated as x. The results are as shown in Table 1.

[0017]

[Table 1]

Next, the durability of the brake hose to repeated pressurization was examined. In this durability test, mounting brackets were fixed to both ends of a brake hose having a length of 200 mm and attached to a testing machine, and at a temperature of 100 ° C., 0 to 100 kgf / cm ^2.
During this period, the pressurization was repeated at a pressurization cycle of 42 cpm, and a swing of ± 50 mm was applied at a swing cycle of 150 cpm. The number of swings until the hose bursts and the state of penetration of the brake fluid into the yarn of the first reinforcing layer of the hose after the durability test were examined. The intermediate rubber layer in the comparative example was formed by winding a rubber tape. The results are as shown in Table 2.

[0019]

[Table 2]

According to the test results, the viscosity of the rubber paste was 200
Below poise, the embedding in the stitch is incomplete and 1
If it exceeds 000 poise, the state of application on the first reinforcing layer 21 becomes incomplete. Therefore, the viscosity of the rubber paste is set to 200 to 100.
At 0 poise, the durability was extremely good. Further, when the brake hose was disassembled after the endurance test, when the NR having a lower permeability of the brake fluid than the SBR of the inner rubber tube was used for the intermediate rubber layer, the brake fluid soaked into the yarn of the first reinforcing layer. Was observed, but was not observed at all in the examples.

[0021]

As described above in detail, in the present invention, the filling rubber layer is formed by forcibly embedding the stitches of the inner first reinforcing layer, so that the first reinforcing layer and the second reinforcing layer are formed in a conventional manner. Together with the abrasion between the yarns in the first reinforcing layer. In addition, the rubber glue forming the filled rubber layer was prepared from rubber having better permeability of brake fluid than the rubber of the inner rubber tube, and only a small layer was formed between the reinforcing layers, so that the rubber paste permeated the inner rubber tube. The brake fluid does not soak into the yarn of the first reinforcing layer and deteriorates. Therefore, the first reinforcing layer is prevented from being worn by the yarns and deteriorated by the brake fluid, and a brake hose having excellent durability under repeated pressure swings can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view of a brake hose according to the present invention.

FIG. 2 is a sectional front view of a main part of a rubber glue tank used for applying rubber glue.

FIG. 3 is a perspective view of a conventional brake hose partially cut away.

FIG. 4 is a partially enlarged sectional view of a conventional brake hose.

[Explanation of symbols]

 Reference Signs List 20 inner rubber tube 21 first reinforcing layer 22 filled rubber layer 23 second reinforcing layer 24 outer rubber tube 25 rubber glue tank 26 through hole 27 through hole 28 rubber ring 29 rubber ring 30 insertion hole 31 insertion hole 34 rubber glue

Claims (5)

(57) [Claims] 1. A brake hose having two braided reinforcing layers of reinforcing yarn between an inner rubber pipe and an outer rubber pipe, wherein a stitch in an inner first reinforcing layer is embedded.
Durability characterized in that a filled rubber layer formed by covering the outer peripheral surface of the reinforcing yarn is formed, and the rubber forming the filled rubber layer is a rubber having better permeability of brake fluid than the rubber of the inner rubber tube. Brake hose. 2. The rubber of the inner rubber tube and the outer rubber tube is ethylene propylene diene rubber, the reinforcing yarn of the reinforcing layer is vinylon yarn, and the rubber of the filling rubber layer is chloroprene rubber. The durable brake hose according to claim 1. 3. The durable brake hose according to claim 1, wherein the filled rubber layer is formed by applying a rubber paste. 4. A hose in which a first reinforcing layer is braided is transferred while being immersed in a rubber glue tank having a viscosity of 200 to 1000 poise while being rubbed with a rubber ring at an outlet of the rubber glue tank. Is forcibly embedded in the stitch
And forming a filled rubber layer covering the outer peripheral surface of the reinforcing yarn . 5. The rubber ring has a rubber hardness of Hs 40 to 7.
5. The method for manufacturing a durable brake hose according to claim 4, wherein the insertion hole through which the hose is inserted is 0.1 to 0.3 mm smaller than the braid diameter of the first reinforcing layer.