JP2007009866A - Flexible joint structure for exhaust pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible joint structure for an exhaust pipe capable of preventing reduction of the diameter of an inner blade without damaging flexibility. <P>SOLUTION: In the flexible joint structure for the exhaust pipe, the inner blade 6 formed by braiding a bundle of heat resistant wire materials 5 spirally crossing with each other in reverse directions to have a cylindrical shape is provided on an inner peripheral face of a hose. As a constraint means for constraining change in a braiding angle of the inner blade 6, a groove type bead 7 extending to the axial center direction of the inner blade 6 is formed in an appropriate portion in the circumferential direction of the inner blade 6 (In the figure, the bead 7 is formed in one portion, but two or more beads can be arranged in a well-balanced manner.). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible joint structure for an exhaust pipe.

  FIG. 6 shows an example of a conventional flexible joint structure of an exhaust pipe. In general, an exhaust pipe 2 to be fixed to the vehicle body 1 (frame in the illustrated example) side is from an engine (not shown). In order to prevent the breaking stress from acting due to vibration, an elastic bellows tube 4 having a bellows structure is interposed between a portion fixed to the vehicle body 1 by the clamp 3 and the engine side.

  In this kind of snake tube 4, when the exhaust pulsation frequency coincides with the natural frequency of the snake tube 4 at a specific engine speed, the snake tube 4 vibrates greatly due to a resonance phenomenon. There was a possibility of adversely affecting the strength and durability.

  For this reason, as shown in an enlarged view in FIG. 7, a bundle of heat-resistant wire rods 5 that intersect with each other in the form of spirals opposite to each other are braided into a cylindrical shape to knitting the inner blade 6, and shown in FIG. Thus, it has been proposed that the inner blade 6 is mounted on the inner peripheral surface of the serpentine tube 4 so that exhaust pulsation does not blow directly onto the concave and convex shape inside the serpentine tube 4, thereby suppressing resonance of the serpentine tube 4.

In addition, there exist the following patent documents 1-4 etc. as prior art document information relevant to this kind of flexible joint structure of an exhaust pipe.
Japanese Utility Model Publication No. 58-124614 Japanese Utility Model Publication No. 58-42485 Japanese Utility Model Publication No. 2-145618 JP-A-7-217431

  However, in the inner blade 6 knitted with the blade as described above, when the inner blade 6 is stretched in the axial direction by an external force such as its own weight or the pressure of exhaust gas, the diamond-shaped stitch of the inner blade 6 (see FIG. 7). Has a property of being reduced in diameter by being flattened long in the axial direction, and if the inner blade 6 is continuously exposed to the heat of the exhaust gas while being expanded in the axial direction and thus being reduced in diameter, the inner blade 6 The inner blade 6 is hardened into a rod shape with a reduced diameter, and the inner blade 6 is swung by the exhaust pulsation while it is hardened into a rod shape, so that abnormal noise is likely to be generated or the inner blade 6 is fixed. The problem is that stress tends to concentrate on the surface.

  In general, if both ends in the axial direction of this type of inner blade 6 are fixed to the inner peripheral surface of the serpentine tube 4 by welding or the like, a large tensile load is applied at the time of large displacement of the expansion / contraction operation of the serpentine tube 4. Or the heat resistant wire 5 is easily cut by repeated stress accompanying the expansion / contraction operation of the serpentine tube 4, so that only the upstream end is fixed to the inner peripheral surface of the serpentine tube 4 by welding or the like, and the downstream side is a free end. However, in particular, in the structure in which the serpentine tube 4 as shown in FIG. 6 is arranged vertically, the downward stretching action due to the weight of the inner blade 6 is effective, and the inner blade 6 The actual situation is that the problem of diameter reduction appears remarkably.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flexible joint structure for an exhaust pipe that can prevent the inner blade from being reduced in diameter without impairing flexibility.

  The present invention relates to a flexible joint structure for an exhaust pipe provided with an inner blade on the inner peripheral surface of a serpentine tube which is formed by braiding a bundle of heat-resistant wire rods that cross in a mutually opposite spiral shape into a cylindrical shape. The restraining means for restraining the change in the braiding angle of the inner blade is partially applied only at an appropriate position of the inner blade.

  In this way, even if the inner blade receives an external force extending in the axial direction, such as its own weight or the pressure of exhaust gas, the change in the braiding angle is restricted only at an appropriate position of the inner blade by the restraining means. As a result, the diamond-shaped stitch is not flattened long in the axial direction at this restrained portion, and diameter reduction is prevented.

  And, if the restraint location by such restraint means is effectively arranged at an appropriate position of the inner blade, it becomes difficult to reduce the diameter because the surrounding restraint location becomes a resistance even for portions other than the restraint location, and the result Therefore, the diameter of the entire inner blade is hindered, and the restraining means only partially restrains the change in the braiding angle only at an appropriate position of the inner blade, so that the flexibility of the entire inner blade is achieved. Will not be damaged.

  In more specific implementation of the present invention, for example, a groove-type bead extending in the axial direction of the inner blade is formed as a restraining means on the inner blade, or the shaft of the inner blade is formed on the inner blade. It is possible to form spot welds at multiple locations in the central direction as restraining means, or to fit an inner blade as a restraining means with a flexible frame that spirals in the axial direction of the inner blade. is there.

  According to the above-described flexible joint structure of an exhaust pipe of the present invention, the inner blade can be prevented from being reduced in diameter without impairing flexibility, so that the inner blade is stretched in the axial direction and remains elongated and reduced in diameter. The trouble that hardens into a rod shape can be avoided without fail, and the inner blade is hardened into a rod shape and swings due to exhaust pulsation and hits the inside of the serpentine tube. It is possible to achieve an excellent effect of preventing the possibility of the concentration and damage of the liquid.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 show a first embodiment of the present invention, and the parts denoted by the same reference numerals as in FIGS. 6 to 8 represent the same items.

  As shown in FIGS. 1 and 2, in this embodiment, the inner braid 6 has a diamond-shaped stitch (see FIG. 7) as a restraining means for restraining a change in the braiding angle so as not to be flattened long in the axial direction. The blade 6 extends in the axial direction of the inner blade 6 at appropriate locations in the circumferential direction of the blade 6 (in the drawing, the case where the blade 6 is formed at one location is illustrated as an example but may be arranged in a balanced manner at two or more locations). A groove-type bead 7 is formed.

  Here, when the groove-type bead 7 is formed on the inner blade 6, for example, as shown in FIG. 3, the inner blade 6 is covered with a cylindrical mold 9 provided with a groove 8, and then the groove 8 is covered with the groove 8. A part of the inner blade 6 in the circumferential direction may be plastically deformed into a groove shape by pressing with a roller 10 along the outside.

  Thus, even if the inner blade 6 receives an external force extending in the axial direction such as its own weight or the pressure of exhaust gas, a part of the inner blade 6 in the circumferential direction becomes a groove shape. Since the bead 7 which is plastically deformed and extends in the axial direction is formed, the change in the braiding angle is restricted by the bead 7 only for a part of the inner blade 6 in the circumferential direction. As a result, at the constrained portion by the bead 7, the diamond-shaped stitch is not flattened long in the axial direction, and the diameter reduction is prevented.

  In addition, the part other than the part where the bead 7 is formed also becomes difficult to reduce the diameter because the constrained part by the bead 7 becomes a resistance. As a result, the diameter reduction of the entire inner blade 6 is prevented, Since the bead 7 only partially restrains the change in the braiding angle only at an appropriate position in the circumferential direction of the inner blade 6, the flexibility of the entire inner blade 6 is not impaired.

  Therefore, according to the above embodiment, the inner blade 6 can be prevented from being reduced in diameter without impairing flexibility, so that the inner blade 6 is stretched in the axial direction and cured into a rod shape while being elongated and reduced in diameter. The inner blade 6 is hardened in a rod shape and is swung by exhaust pulsation and hits the inside of the snake tube 4 (see FIGS. 6 and 8). It is possible to prevent the possibility of stress concentration and damage to the fixed portion 6.

  FIG. 4 shows a second embodiment of the present invention. In this embodiment, as a restraining means for restraining a change in the braiding angle of the inner blade 6, the entire inner blade 6 is alternately spotted in a well-balanced manner. A large number of spot welds 11 are formed by welding.

  Thus, in this way, the change in the braiding angle is partially restricted only at the locations where the respective spot welds 11 are formed, and the peripheral spots are also applied to portions other than the respective spot welds 11. Since the constrained portion by the welded portion 11 becomes resistance and it is difficult for the inner diameter of the inner blade 6 to be reduced, each spot welded portion 11 is partially only at an appropriate position of the inner blade 6. Since only the change in the braiding angle is constrained, the flexibility of the entire inner blade 6 is not impaired.

  Therefore, even when such a second embodiment is adopted, the inner blade 6 can be prevented from being reduced in diameter without impairing flexibility, so that the inner blade 6 is elongated in the axial direction so as to be elongated and reduced in diameter. Therefore, it is possible to surely avoid the problem that the inner blade 6 is hardened to a rod shape, and the inner blade 6 is swung by the exhaust pulsation while being hardened to a rod shape. It is possible to prevent the possibility of stress concentration and damage to the fixed portion.

  Further, FIG. 5 shows a third embodiment of the present invention. In this embodiment, a spiral is formed in the axial direction of the inner blade 6 as a restraining means for restraining a change in the braiding angle of the inner blade 6. The formed flexible frame 12 is suspended inside the inner blade 6 and is fitted inside. More specifically, the upper end portion of the flexible frame 12 is fixed to the upper end portion of the inner blade 6 by welding. The lower end of the flexible frame 12 is a free end that is suspended as it is.

  Thus, in this way, the diameter reduction is partially prevented only at the place where the spiral flexible frame 12 is fitted, and the change in the braiding angle is restrained. Since the inner fitting locations of the upper and lower flexible frames 12 also become resistance and are difficult to reduce the diameter of the portion where the flexible frame 12 is not fitted, the diameter reduction of the entire inner blade 6 is prevented. However, since the flexible frame 12 only partially restrains the change of the braiding angle only at an appropriate position of the inner blade 6, the flexibility of the inner blade 6 as a whole is not impaired.

  Therefore, even when such third embodiment is adopted, the inner blade 6 can be prevented from being reduced in diameter without impairing flexibility, so that the inner blade 6 is elongated in the axial direction to be elongated and reduced in diameter. Therefore, it is possible to surely avoid the problem that the inner blade 6 is hardened to a rod shape, and the inner blade 6 is swung by the exhaust pulsation while being hardened to a rod shape. It is possible to prevent the possibility of stress concentration and damage to the fixed portion.

  In addition, the flexible joint structure of the exhaust pipe of the present invention is not limited to the above-described embodiment, and the groove-type beads formed as restraining means are formed at two or more locations in the circumferential direction of the inner blade. In addition, the groove shape may be convex outward in the radial direction, and various changes can be made without departing from the scope of the present invention. is there.

It is a perspective view which shows the 1st example of a form of this invention. It is a cross-sectional view of the inner blade of FIG. It is explanatory drawing which shows an example of the means to form a bead in the inner blade of FIG. It is a perspective view which shows the 2nd example of a form of this invention. It is a side view which shows the 3rd example of a form of this invention. It is a side view which shows an example of the flexible joint structure of the conventional exhaust pipe. FIG. 7 is an enlarged view showing details of an inner blade provided in the serpentine tube of FIG. 6. It is sectional drawing which shows the detail of the VIII part of FIG.

Explanation of symbols

2 Exhaust pipe 4 Snake pipe 5 Heat-resistant wire 6 Inner blade 7 Bead (restraint)
11 Spot welds (restraint means)
12 Flexible frame (restraint means)

Claims (4)

  A flexible joint structure of an exhaust pipe provided with an inner blade knitted by knitting a bundle of heat-resistant wire rods crossing in a mutually opposite spiral shape into a cylindrical shape, A flexible joint structure for an exhaust pipe, wherein a restraining means for restraining a change in the braiding angle of the inner blade is partially applied only at an appropriate position of the inner blade.   2. The flexible joint structure for an exhaust pipe according to claim 1, wherein a groove-type bead extending in the axial direction of the inner blade is formed as a restraining means with respect to the inner blade.   2. The flexible joint structure for an exhaust pipe according to claim 1, wherein spot welds are formed as restraining means at a plurality of locations in the axial direction of the inner blade relative to the inner blade.   The flexible joint structure for an exhaust pipe according to claim 1, wherein a flexible frame having a spiral shape in the axial direction of the inner blade is fitted into the inner blade as a restraining means.

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