JP5287411B2 - Expansion fitting - Google Patents

Description

  The present invention relates to an expansion joint that absorbs deformation and expansion of piping.

  Basically, the expansion joint has a function of absorbing displacement (displacement displacement) due to displacement of the mounting position of the connected pipe, displacement due to expansion / contraction of the piping (expansion displacement), and the like, for example, as shown in FIG. The bellows (bellows tube) 1 has a bellows structure in which an inlet flange 2 is connected to an end portion where the internal fluid enters, and an outlet flange 3 is connected to an end portion where the internal fluid exits.

However, because the expansion joint has a bellows structure, it has a large pressure loss unlike a straight pipe, and when the bending displacement of the pipe is absorbed and deformed, the pressure loss further increases and the internal fluid pressure is affected. There is a problem to do.
As a solution to this problem, there are the following conventional techniques.
(1) Each bellows portion of the bellows is filled with an elastic material, and a biaxially stretchable film is bonded to the inner surface of the bellows so as to close the opening in each mountain shape portion (Patent Document 1).

  (2) A straight pipe-shaped inner cylinder is arranged inside the bellows with a gap between the outer surface of the inner cylinder and the inner surface of the bellows, and the outlet end of the inner cylinder is free and the outlet end of the inner cylinder The part is fixed by welding to the flange on the same side (or pinching at the same side bent part of the bellows) (Patent Document 2 or Patent Document 3).

Japanese Examined Patent Publication No. 6-37954 JP 2002-113433 A Japanese Utility Model Publication No. 63-28992

However, in the prior art (1), the pressure loss can be sufficiently reduced. However, since the manufacture is made by integrating the bellows, the elastic material, and the film, time and cost are increased.
Further, in the prior art (2), the manufacturing time and cost increase are small, but as shown in FIG. 2, for example, the inner end of the inner cylinder 4 is fixed and the inner surface of the bellows 1 and the inner cylinder 3 are fixed. Since the gap 5 is provided between the outer surface and the outer surface, the flexibility with respect to the deviation is provided. Therefore, when further improving the flexibility with respect to the deviation, it is necessary to reduce the inner cylinder diameter. This is disadvantageous for reducing pressure loss. On the other hand, when the inner cylinder diameter is increased, the gap between the bellows and the inner cylinder is reduced and the flexibility is impaired.

  As described above, the conventional low-cost expansion joint has a problem that it is difficult to achieve both reduction in pressure loss and flexibility.

The present invention has been made for the purpose of providing an expansion joint that can achieve both pressure loss reduction and flexibility in a low-cost expansion joint having an inner cylinder that solves the above-mentioned problems. It is.
(1) An expansion joint having an inlet flange at the inlet end of the bellows, an outlet flange at the outlet end, and an inner cylinder inside the bellows, and an inner cylinder flange portion at the inlet end of the inner cylinder The expansion joint is characterized in that a flange portion gap is provided in which the exit surface of the inner cylinder flange portion faces the entry surface of the entry flange, and a gap is created between the faces.

  According to the present invention, the inner cylinder flange portion is provided at the inlet end portion of the inner cylinder, the exit surface of the inner cylinder flange portion faces the entrance surface of the inlet flange, and a gap is generated between the facing surfaces. By providing the flange gap, in the low-cost expansion joint provided with the inner cylinder, an expansion joint that achieves both pressure loss reduction and flexibility can be realized.

Schematic cross section showing one example of basic expansion joint Schematic sectional view showing an example of a conventional expansion joint Schematic sectional view showing an example of the expansion joint of the present invention Schematic sectional view showing a state of deformation corresponding to displacement displacement of the expansion joint of the present invention

  An example of the expansion joint of the present invention is shown in FIG. In FIG. 3, the bellows 1 has an inlet flange 2 at the inlet end and an outlet flange 3 at the outlet end, and an inner cylinder 4 (outer diameter A, length B, gap amount of gap 5 inside the bellows 1. E) is the same as in the prior art (FIG. 2), but unlike the conventional one in which the inlet end of the inner cylinder 4 is fixed to the inlet flange 2, in the present invention, the inlet side of the inner cylinder 4 is used. An inner cylinder flange 6 (diameter C) is provided at the end, the exit side of the inner cylinder flange 6 faces the entry side of the entry flange 2, and a gap 7 (gap amount D) is generated between the faces. The flange part gap 8 to be made was provided. The flange portion gap 8 is formed as a cavity in which the inner cylinder flange portion 6 is loosely fitted. In this example, the cavity is formed on the entry side of the entry flange 2, but instead of or in addition to this, on the exit side of the pipe flange 10 connected to the entry flange 2. May be formed.

In the prior art (FIG. 2), since the inner cylinder 4 is fixed, the movable range of the bellows 1 due to the displacement is limited within the gap 5, and the allowable displacement displacement δ of the bellows 1 is the gap amount E of the gap 5. That is, δ = E. Therefore, in order to improve flexibility, the inner cylinder diameter must be reduced and the gap 5 must be increased. Therefore, the pressure loss increases.
On the other hand, in the present invention, the inner cylinder flange portion 6 is freely displaced within the flange portion gap 8 by the above-described configuration, so that the bellows 1 is deformed and contacts the inner cylinder 4 as shown in FIG. Even if the inner cylinder 4 is pushed, the inner cylinder 4 tilts to the limit of its free displacement, so that the movable range of the bellows 1 is expanded outside the gap 5. That is, the allowable deviation displacement amount δ in the present invention is larger than the conventional E (FIG. 2) by the displacement amount X = B × (D / C) accompanying the tilting of the inner cylinder 4, and δ = E + X = E + B ×. (D / C). Therefore, according to the present invention, unlike the conventional case (FIG. 2), it is not necessary to reduce the inner cylinder diameter (increase the pressure loss) in order to improve flexibility, and both reduction of pressure loss and flexibility are achieved. be able to.

(Comparative Example 1)
As Comparative Example 1, in FIG. 3, A = 60 mm, B = 60 mm, C = 90 mm, D = 0 mm (the inner cylinder 4 is fixed to the inlet flange 2 by welding, the gap 7 is eliminated, and the same form as FIG. And E = 20 mm. In Comparative Example 1, the allowable deviation displacement amount δ is δ = E = 20 mm.
(Example of the present invention)
As an example of the present invention, in FIG. 3, A = 60 mm, B = 60 mm, C = 90 mm, D = 10 mm, and E = 20 mm. In the example of the present invention, the allowable displacement amount δ is δ = E + X = E + B × (D / C) = 20 + 60 × (10/90) = 26.7 mm, and the allowable displacement amount is 6. The advantage is 7mm larger.
(Comparative Example 2)
As Comparative Example 2, the outer diameter of the inner cylinder 4 was changed in Comparative Example 1 so as to achieve the same allowable displacement displacement amount as that of the present invention example. In this case, the outer diameter A of the inner cylinder before the change and the outer diameter A ′ of the inner cylinder after the change are 2 × E + A = 2 × (E + X) + A ′ (= bellows end inner diameter; constant). Have. Therefore, A ′ = A−2 × X = A−2 × B × (D / C) = 60−2 × 60 × (10/90) = 46.6 mm, and the inner cylinder outer diameter of Comparative Example 2 is 46.6 / 60 = 0.77 times that of the example of the present invention. Here, for the sake of simplicity, the inner diameter of the inner cylinder is also regarded as 0.77 times that of the example of the present invention. If the volume flow rate of the fluid flowing in the inner cylinder is constant, the flow velocity is inversely proportional to the square of the inner cylinder inner diameter, and the pressure loss is proportional to the square of the flow velocity. In comparison with the example of the present invention, (1 / 0.77) ⁴ = about 2.7 times. In other words, the example of the present invention is superior to the comparative example 2 having the same allowable deviation displacement amount by the amount that the pressure loss can be suppressed to about 1 / 2.7.

1 Bellows 2 Incoming flange 3 Outgoing flange 4 Inner cylinder 5 Gap 6 Inner cylinder flange 7 Clearance 8 Flange gap
10 Piping flange

Claims (1)

  In an expansion joint having an inlet flange at the inlet end of the bellows, an outlet flange at the outlet end, and an inner cylinder inside the bellows, an inner cylinder flange portion is provided at the inlet end of the inner cylinder, An expansion joint, characterized in that a flange portion gap is provided in which the exit surface of the inner cylinder flange portion faces the entry surface of the entry flange, and a gap is created between the face surfaces.

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