JPS6115353Y2 - - Google Patents

Description

[Detailed description of the invention] ...Field of industrial application The present invention relates to the configuration of a pressure-balanced bellows-type pipe joint for straight piping, and has the same operating principle as the conventional pressure-balanced bellows-type pipe joint. However, the structure is extremely simplified and the drawbacks of conventional joints are overcome.

Bellows type joints have the ability to expand and contract with a slight load. However, because of this, the joint stretches even with a small internal pressure, so it is necessary to restrain it. In addition, with the exception of some articulated joints, two or more bellows-type joints should not be installed between fixed points, and if two or more joints are installed in straight piping, an intermediate fixed point must be provided. There must be.

The main fixing points are provided at the starting point, end point, bending point, branching point, valve installation location, etc. of the piping, and the load (reaction force) received is a composite value of the thrust force due to internal pressure and the load due to expansion and contraction.

F = Fp + Fe Fp = S ×P Fe = Ko × δ S = π/4 (D + d/2) ² Ko = K / N F = Total load acting on the fixed point Kg Fp = Thrust due to internal pressure Kg Fe = Due to specified compression Load Kg S = Pressure-receiving area of the bellows cm ² P = Internal pressure (depending on the fluid in the pipe) Kg/cm ² Ko = Spring constant of the joint Kg/mm δ = Compression amount mm D = Outer diameter of the bellows cm d = Inner diameter of the bellows cm K = Spring constant of bellows Kg/mm/1 thread N = Number of threads of bellows As is clear from the above, in piping that uses bellows type joints, the strength of the fixing point is the most important thing, and that strength is determined by the internal pressure The joint cannot operate effectively unless the thrust force Fp is equal to or greater than the combined value of the load Fe required for expansion and contraction.

Therefore, in high-pressure or large-diameter piping, the load (reaction force) F applied to the fixed point is extremely large, and of this, Fp
The value accounts for a large proportion. Therefore, in order to reduce the load applied to the fixed point, the Fp value can be reduced or eliminated, and pressure-balanced pipe fittings were developed to meet this requirement.

Pressure balance type pipe fittings are broadly divided into two types: those for curved pipes (branch pipes) and those for straight pipes (straight piping).
The principle of action is the same for both bellows, and in short, a sub bellows with a pressure receiving area (basically) equal to the pressure receiving area of the main bellows attached to the pipe (the area receiving the thrust Fp due to the internal pressure P due to the fluid in the pipe) is installed in conjunction with the bellows. The thrust force Fp on the main and sub bellows is applied in opposite directions to eliminate the thrust force Fp, so that the thrust force Fp does not affect the fixed point and only the load Fe required for expansion and contraction is It is designed to work.

Among the above, pressure-balance type pipe joints for straight pipes are axial type joints that are installed in the middle of straight pipes and have a structure that reduces the load (reaction force) F applied to the fixed point. It is used when sufficient strength at the fixing point cannot be obtained due to the diameter, rack-mounted piping, high-pressure piping, etc., but conventional pipe joints of this type have the disadvantage of having a complicated structure and a large outer diameter.

...Conventional Example (1) The conventional pressure-balanced pipe joint for straight pipes has bellows A1 and A2 with the same diameter as the pipe, and bellows twice the diameter of A1 and A2, as shown in Figure 1A. B with pressure receiving area (basic) S of (A1 + A2)
Connect A1 and B with a rod or frame with the bellows,
B and A2 have a connected structure regardless of A1.

The thrust force Fp due to the internal pressure P operates in the opposite direction so that the B bellows at the middle part of the joint shortens the distance between the joint surfaces, so the thrust force Fp no longer affects the fixed point. The bellows expansion/contraction operation is as shown in Figure 1 (B), and the distances between A1+B and B+A2 remain unchanged even when the bellows is expanded/contracted, and when the pipe joint contracts, A1 and A2
B contracts and B expands, and when the pipe joint stretches, B contracts.
A1 and A2 stretch. Some pipe joints of this type have a configuration in which the arrangement of the bellows A1, B1, and A2 is changed, but the principle of operation is the same.

In either case, the diameter of the B bellows had to be made considerably large due to its configuration, which resulted in a drawback.

...Prior art example (2) In addition to the above conventional example, for example,
No. 96864 (Utility Model Publication No. 46-5015), the name of the invention is "Expansible Pipe Joint," which has the same basic principle as the present invention. A pipe joint has also been considered in which a balance bellows 4 closed by a lid 3 is placed parallel to and opposite to a tubular bellows 5, and the balance bellows is expanded and contracted in conjunction with the tubular bellows in the opposite direction when the tubular bellows expands and contracts. In some cases, it has not been possible to obtain a concrete structure that is simple, strong, and does not take up much space in order to effectively demonstrate its basic principles, and as a result, it has not been put into practical use to this day.

...Structure of the present invention Although the present invention has the same basic principle as the conventional pressure-balanced bellows type pipe joint described above, the specific structure has been extremely simplified and has been successfully put into practical use. , which eliminates the drawbacks of the above conventional joints.

Next, to explain the structure of the present invention, at least one sub bellows with both ends closed is installed in the vicinity of the main bellows attached to the piping, and the main and sub bellows move in opposite directions when expanding and contracting. A pressure-balanced bellows-type pipe joint that connects the two appropriately with a connecting rod, etc. so that they can work together, and also has a bypass that circulates the fluid in the pipe between the main and sub-bellows to equalize the internal pressure of the main and sub-bellows. , a secondary bellows B (basically the same diameter as the main bellows A in terms of design) with both ends appropriately closed with a cover plate 2 etc. is installed in the vicinity of the main bellows A to be attached to the pipe 1 between fixed points (not shown). The main bellows A and B are installed so that they act in exactly opposite directions when they expand and contract, that is, the main bellows A expands (bends and contracts).
Then, the secondary bellows B bends and contracts (expands).
In order to ,main,
Between the left and right ends of sub bellows A and B (L vs. L', R vs.
Bypass 4 that circulates the fluid in the pipe to make the internal pressure P of the main and sub bellows A and B the same (between R')
For example, these are connected using flexible tubes or flexible pipes. (Fig. 2) That is, to describe a specific embodiment of the present invention with reference to Figs. , a rib 12 and a flange 8 connected to the pipe 1 are integrally provided, and the sub bellows B is a short pipe in which an adjustment flange 9, an adjustment rod nut 10, and a cover plate 2 are sealed and fixed around the bellows B. 11 and ribs 13 are integrally provided. One end of the connecting rod 3a is welded to the adjustment flange 5 and rib 12 near the left end L of the main bellows A, and the other end is welded to the adjustment flange 9 and rib 13 near the right end R' of the sub bellows B. The connecting rod 3b is fixed and partially overlaps with 3a, and has one end attached to the adjustment flange 5 and rib 12 near the right end R of the main bellows A, and the other end attached to the adjustment flange 5 and rib 12 near the left end L' of the sub bellows B. flange 9 and rib 13
A small shaft 14 protruding from the surface of the connecting rod 3a and a slit 15 bored on the surface of the connecting rod 3b.
The pair of connecting rods 3a and 3b are inserted into and engaged with each other.
The main and sub bellows A and B are formed symmetrically on the front and back surfaces, so that, for example, when the main bellows A is extended, the connecting rods 3a and 3b are interlocked and the sub bellows B is bent and contracted.

Furthermore, a bypass 4 consisting of a flexible tube etc.
Between the short pipe 7 near the left end L of the main bellows A and the short pipe 11 near the left end L' of the sub bellows B, and the main bellows A
Near the right end of R short pipe 7 and sub bellows B near the right end
The short pipes 11 of R' are connected to each other so that the fluid in the pipes circulates into the sub bellows B through the bypass 4,
In other words, the fluid internal pressures P of the main and sub bellows A and B are made to be the same.

In the above configuration, the proposed pipe joint has a basic design in which the pressure receiving areas S of the main and sub bellows A and B are made equal (for example, bellows of the same diameter and the same cross-sectional area are used as the main and sub bellows A and B). ), the thrust force Fp due to the internal pressure due to the fluid in the pipe
is applied to the main bellows A, the equal thrust Fp
However, due to the interlocking action of the intersecting connecting rods 3, the thrust forces Fp of the two act in opposite directions and are pulled together to balance each other. Therefore,
The thrust force Fp that attempts to extend the main bellows A is effectively canceled by the thrust force Fp of the secondary bellows B that acts in the opposite direction.

Therefore, the thrust force Fp does not affect the fixed point of the piping, and only the expansion/contraction load Fe of the bellows acts on it.

Basically, it is sufficient to set the pressure receiving areas of the main and sub bellows A and B to be equal as described above, but it is possible to change the setting values as necessary and adjust the design according to the application etc. Needless to say, the set value is not limited to adjusting the diameter of the bellows.

In addition, it is naturally possible to provide two or more sub bellows mainly due to the installation position and space requirements, by applying the above configuration example of the present invention. The structure and its installation will change slightly.

...Effects of the present invention The pressure-balanced bellows-type pipe joint of the present invention has the above-mentioned configuration and function, so it has the following extremely superior advantages compared to the conventional pressure-balanced bellows-type pipe joint for straight pipes. be.

(b) Compared to the conventional example (1) (1) Compared to the conventional joint, the structure can be extremely simplified without changing the principle of operation and its effects,
For example, conventional joints require a total of three main and sub bellows, but the present invention requires only two main and sub bellows (example).

(2) The overall length of the joint itself was inevitably long because conventional joints were installed in parallel on the piping axis, but in this invention only the main bellows is installed on the piping axis, and the secondary bellows is installed off the axis. By doing so, we were able to reduce the time to less than 1/2 compared to the conventional method.

(3) Conventional joints had the disadvantage that the secondary bellows B had to be made large in diameter, which meant that they could not be installed in parallel piping with particularly narrow parallel spacing, but the present invention has the disadvantage that the main bellows B cannot be installed. The secondary bellows can be installed outside the row of parallel piping (for example, above, below, etc.) if they are spaced apart as much as possible. This is the greatest feature of the present invention.

(4) Due to the features 2 and 3 above, compared to conventional joints, there are far fewer restrictions on position space and installation locations, and the range of uses can be expanded.

(5) Since there is no need for large-diameter bellows, and there is only one less bellows, the weight can be reduced to approximately 1/2 of that of conventional joints, and production costs can be significantly reduced.

(b) Compared to conventional example (2)... (1) Conventional example (2) has the same basic construction principle as the present invention, but its specific construction is compact, simple, strong, However, as it was, we were unable to complete a component that operated smoothly, and as it was, it was completely unsuitable for practical use.However, as mentioned above, the present invention is compact and does not take up much space, making it ideal for practical use. By developing a concrete structure that is simple, strong, and has extremely accurate and smooth operation, we have been able to put the above basic principle into practical use, thus providing an unprecedented pressure-balanced bellows type pipe joint. It is possible.

[Brief explanation of the drawing]

In Fig. 1, A is a cross-sectional explanatory diagram showing the general configuration of a conventional pressure-balanced bellows-type pipe joint, B is an explanatory diagram showing its working principle, and Fig. 2 is a diagram of the pressure-balanced bellows-type pipe joint according to the present invention. FIG. 3 is a partially cutaway front view of a specific embodiment of the joint of the present invention, and FIG. 4 is a cross-sectional view taken along A'-A'' of FIG. 3. A...Main bellows, B...Secondary bellows,
F...Load (reaction force), Fp...Thrust due to internal pressure P due to fluid in the pipe, Fe...Bellows expansion/contraction load, S
...Pressure receiving area, L, L'...near the left end of the bellows,
R, R'... Near the right end of the bellows, 1... Piping,
2...Lid plate, 3, 3a, 3b...Connecting rod, 4...
Bypass, 5...Adjustment flange, 6...Adjustment rod nut, 7...Short pipe, 8...Flange, 9
... Adjustment flange, 10 ... Adjustment rod nut, 11 ... Short pipe, 12, 13 ... Rib, 14 ...
...Small axis, 15...slit.

Claims (1)

[Claims for Utility Model Registration] At least one sub bellows with both ends closed is installed in the vicinity of the main bellows attached to the piping, so that the main and sub bellows operate in conjunction with each other in opposite directions when they expand and contract. In a pressure-balanced bellows-type pipe joint, the two are appropriately connected by a connecting rod, etc., and a bypass is provided to circulate the fluid in the pipe between the main and sub-bellows in order to equalize the internal pressure between the main bellows A. , the adjusting flange 5, the adjusting rod nut 6, the short pipe 7, the rib 12, and the flange 8 connecting to the piping 1 on the left and right with the bellows a as the center.
is integrally provided, while the secondary bellows B
, the adjustment flange 9 centering on the bellows b,
The adjustment rod nut 10, the short pipe 11 to which the cover plate 2 is sealed and fixed, and the rib 13 are integrally provided, and one end of the connecting rod 3a is connected to the adjustment flange 5 and the rib 12 near the left end L of the main bellows A. The other end is welded and fixed to the adjusting flange 9 and the rib 13 near the right end R' of the sub bellows B. The connecting rod 3b is partially overlapped with the connecting rod 3a, and one end is attached to the main bellows. The other end is attached to the adjustment flange 5 and rib 12 near the right end R of A, and the other end is attached to the adjustment flange 9 and rib 13 near the left end L' of sub bellows B.
A small shaft 1 is fixedly welded to each side and protrudes from the surface of the connecting rod 3a.
4 is inserted into and engaged with a slit 15 drilled in the surface of the connecting rod 3b, and the pair of connecting rods 3a and 3b is
Bypasses 4, 4 made of flexible tubes are formed symmetrically on the front and back surfaces of the main and sub bellows A and B, and a short pipe 7 near the left end of the main bellows A and a short pipe near the left end L' of the sub bellows B are connected. 11, and near the right end of the main bellows A, near the right end of the short pipe 7 of R, and the right end of the sub bellows B.
Pressure-balanced bellows-type pipe joint connected between short pipes 11 and 11 of R'.