JP2006242285A - Piping joint seal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure of a pipe joint portion having a high degree of freedom in selecting a material of a shape memory alloy.
SOLUTION: In a seal structure of a pipe joint portion 1 that seals between a pipe 11 (first fluid pipe) and a pipe 12 (second fluid pipe) inserted at an end thereof, the pipe 11 is provided outside the pipe 11. A shape memory alloy ring 4 that is externally fitted and tightens the pipe 11 to the pipe 12 side is provided, and the shape memory alloy ring 4 is configured such that an inner diameter at a predetermined transformation temperature or higher is smaller than an inner diameter at a temperature lower than the transformation temperature. ing. A sealing material 5 is provided between the pipe 11 and the pipe 12.
[Selection] Figure 1

Description

  The present invention relates to a seal structure of a pipe joint portion that hermetically seals and / or seals between a first fluid pipe and a second fluid pipe inserted at an end thereof.

As a seal structure of a pipe joint part widely used in general industries, a technique using a shape memory alloy as a seal material is known. For example, in the seal structure disclosed in Patent Document 1, a seal material made of a shape memory alloy is interposed between flange joint surfaces of fluid pipes connected to each other. Since the shape memory alloy can be repeatedly used as a sealing material and can be applied to a high-temperature and high-pressure fluid, high sealing performance can be realized while saving costs and resources.
Japanese Patent Application Laid-Open No. 07-239036

  However, in the seal structure of Patent Document 1, since the shape memory alloy that is the seal material is in direct contact with hydrogen flowing in the pipe, there is a problem that the material selection of the shape memory alloy is restricted from the viewpoint of strength and corrosion resistance. there were. Such a problem can also occur when a fluid other than hydrogen flows in the pipe depending on the combination of the type and state (pressure, temperature, etc.) of the fluid flowing in the pipe and the shape memory alloy.

  The present invention has been made in view of the above circumstances. In a seal structure of a pipe joint portion in which a joint portion between fluid pipes is a fitting structure, and a shape memory alloy ring is provided on the outer periphery of the fitting portion. An object is to increase the degree of freedom in selecting the material of the shape memory alloy.

  In the present invention, the following means are adopted in order to solve the above problems. That is, the invention according to claim 1 is a seal structure of a pipe joint part that hermetically seals and / or seals between a first fluid pipe and a second fluid pipe inserted at an end thereof. A shape memory alloy ring that is extrapolated to the outside of the first fluid pipe and tightens the first fluid pipe to the second fluid pipe side has an inner diameter at a predetermined transformation temperature or higher. It is characterized by being smaller than the inner diameter below the transformation temperature.

  According to the configuration of the present invention, when the shape memory alloy ring becomes equal to or higher than a predetermined transformation temperature due to, for example, an increase in piping pressure or fluid temperature, the shape memory alloy ring is reduced in diameter compared with the previous state. Therefore, the first fluid piping tightens the second fluid piping, and the seal pressure between these fluid pipings increases. Since the shape memory alloy ring itself is provided outside the first fluid pipe, it does not directly contact the fluid flowing in the fluid pipe. For this reason, the range of the material selection of the shape memory alloy which has restrictions, such as intensity | strength and corrosion resistance, can be expanded.

  The invention according to claim 2 is characterized in that, in the seal structure of the pipe joint part according to claim 1, a seal material is provided between the first fluid pipe and the second fluid pipe. To do.

  According to the configuration of the present invention, the seal between the first fluid pipe and the second fluid pipe is reliably performed.

  In this configuration, it is preferable that the linear expansion coefficient of the second fluid pipe is larger than the linear expansion coefficient of the first fluid pipe. As the fluid pressure rises, the temperature rises accordingly. Therefore, if “the linear expansion coefficient of the second fluid piping ≦ the linear expansion coefficient of the first fluid piping”, the diameter of the first fluid piping is the first. It is because it becomes larger than the diameter of 2 fluid piping, and the tension | tensile_strength to a sealing material becomes weak.

  On the other hand, according to the said structure, when the fluid pressure is high, the tension | tensile_strength to a sealing material can be raised. This means that it is not necessary to set an excessive amount for the sealing material according to the condition where high sealing performance is required, so the sealing material can be made smaller when the fluid pressure is low, The generation of creep can be suppressed.

  For example, when applied to an “autoclave-type joint” in which fluid pipes are in direct metal contact, the sealing material according to the configuration of the present invention is unnecessary.

  The invention according to claim 3 is the seal structure of the pipe joint part according to claim 1 or 2, wherein the first fluid pipe and the second fluid pipe are for high-pressure hydrogen.

  The seal structure of the pipe joint part according to the present invention is preferably used for high-pressure hydrogen pipes that have restrictions on the selection of shape memory alloys. In such a case, since the shape memory alloy ring does not come into direct contact with hydrogen, there is no possibility of hydrogen embrittlement and the degree of freedom in material selection is increased.

  In the present invention, by tightening the joint portion from the outside using the shape memory alloy ring, the sealing performance between the first and second fluid pipes in the joint portion is ensured. It is possible to provide a pipe joint seal structure having a high degree of freedom.

  One embodiment of a seal structure for a pipe joint according to the present invention will be described below. FIG. 3 shows a fuel cell system according to an application example of the present invention. Air (outside air) as an oxidizing gas is supplied to an air supply port of the fuel cell 20 via an air supply path 71. The air supply path 71 is provided with an air filter A1 that removes particulates from the air, a compressor A3 that pressurizes the air, a pressure sensor P4 that detects the supply air pressure, and a humidifier A21 that adds required moisture to the air.

  The air off gas discharged from the fuel cell 20 is discharged to the outside through the exhaust path 72. The exhaust path 72 is provided with a pressure sensor P1 for detecting the exhaust pressure, a pressure regulating valve A4, and a heat exchanger for the humidifier A21.

  Hydrogen gas as fuel gas is supplied from a hydrogen supply source (for example, a high-pressure hydrogen tank) 30 to a hydrogen supply port of the fuel cell 20 through a fuel supply path 74. The fuel supply path 74 includes a shutoff valve H100 that supplies or stops supplying hydrogen from the hydrogen supply source 30, a pressure sensor P6 that detects the supply pressure of hydrogen gas from the hydrogen supply source 30, and hydrogen gas to the fuel cell 20. The pressure regulating valve H9 for reducing and adjusting the supply pressure of the fuel, the pressure sensor P9 for detecting the hydrogen gas pressure downstream of the hydrogen pressure regulating valve H9, and the shutoff valve H21 for opening and closing between the hydrogen supply port of the fuel cell 20 and the fuel supply path 74. And a pressure sensor P5 for detecting the inlet pressure of the hydrogen gas fuel cell 20 is provided.

  The hydrogen gas that has not been consumed in the fuel cell 20 is discharged as hydrogen off-gas to the hydrogen circulation path 75 and returned to the downstream side of the pressure regulating valve H9 in the fuel supply path 74. The hydrogen circulation path 75 includes a temperature sensor T31 for detecting the temperature of the hydrogen off-gas, a shutoff valve H22 for communicating / blocking the fuel cell 20 and the circulation path 75, a gas-liquid separator H42 for recovering moisture from the hydrogen off-gas, and a recovered generation. A drain valve H41 that collects water in a tank (not shown) outside the circulation path 75, a hydrogen pump H50 that pressurizes hydrogen off-gas, and a backflow prevention valve (check valve) H52 are provided. The hydrogen circulation path 75 is connected to the exhaust path 72 by a purge flow path 76 via a discharge control valve (purge valve) H51.

  Furthermore, a cooling path 73 for circulating the cooling water is provided at the cooling water inlet / outlet of the fuel cell 20. In the cooling path 73, a temperature sensor T1 that detects the temperature of the cooling water drained from the fuel cell 20, a radiator (heat exchanger) C2 that radiates the heat of the cooling water to the outside, and a pump that pressurizes and circulates the cooling water. A temperature sensor T2 for detecting the temperature of the cooling water supplied to C1 and the fuel cell 20 is provided. The radiator C2 is provided with a cooling fan C13 that is rotationally driven by a motor.

  The fuel cell 20 is configured as a fuel cell stack in which a required number of fuel cells (unit cells) are stacked, and generates power using hydrogen supplied from the hydrogen supply source 30 as fuel.

The control unit 50 receives control information from a requested load such as an accelerator signal of a vehicle (not shown) and sensors (pressure sensor, temperature sensor, flow rate sensor, output ammeter, output voltmeter, etc.) of each part of the fuel cell system. FIG. 1 shows two fuel cells used when charging the hydrogen supply source 30 of the fuel cell system with high-pressure hydrogen and releasing hydrogen from the hydrogen supply source 30. The pipe joint part 1 formed by connecting the pipes in the axial direction is shown. In this pipe joint 1, another pipe (second fluid pipe) 12 extending to the fuel cell 20 side is inserted into one end of a pipe (first fluid pipe) 11 connected to the hydrogen supply source 30. It is connected. These pipes 11 and 12 constitute a part of the fuel supply path 74.

  The pipe joint portion 1 includes a shape memory alloy ring 4 that is fitted on the outside of the pipe 11 and fastens the pipe 11 to the pipe 12 side, and an annular seal material 5 interposed between the pipe 11 and the pipe 12. ing. The shape memory alloy ring 4 has a short cylindrical shape and is configured such that an inner diameter at a predetermined transformation temperature or higher is smaller than an inner diameter at a temperature lower than the transformation temperature. The inner diameter in the room temperature state is configured to be smaller than the outer diameter of the pipe 11.

  As the shape memory alloy ring 4, for example, a shape memory alloy such as TiNi, Cu, or Fe is used. Since this shape memory alloy ring 4 does not directly contact the hydrogen flowing in the pipes 11 and 12, in addition to these illustrated shape memory alloys, various shape memory alloys that do not cause hydrogen embrittlement should be used. Is possible.

  The outer diameter of the pipe 12 is smaller than the inner diameter of the pipe 11 and is inserted into the pipe 11. Further, the linear expansion coefficient of the pipe 12 is larger than the linear expansion coefficient of the pipe 11.

  At the time of pipe connection, the pipe 12 is inserted into the pipe 11 with the sealing material 5 interposed therebetween, and the shape memory alloy ring 4 is press-fitted into the pipe 11 from the outside of the pipe 11. At this time, since the seal 5 is interposed between the pipe 11 and the pipe 12, the fluid (hydrogen) flowing through the pipe is reliably sealed.

  When the hydrogen supply source 30 is filled with hydrogen, as shown in FIG. 2A, the gas pressure increases with time and is compressed, thereby increasing the temperature. When the shape memory alloy ring 4 reaches a predetermined transformation temperature or higher, the diameter is reduced, and the pipe 11 tightens the pipe 12. Since the piping 12 has a larger linear expansion coefficient than the piping 11, the expansion amount in the radial direction of the piping 12 due to the temperature rise is larger than the expansion amount of the piping 11. Accordingly, as the gas pressure increases, the tightening allowance between the pipe 11 and the pipe 12 is further increased, and the sealing performance is improved.

  When hydrogen is released, the pressure gradually decreases with temperature as shown in FIG. 2B, and the inner pipe 12 contracts accordingly.

  As described above, the seal structure of the pipe joint portion 1 according to the present embodiment has a fitting structure for the joint portion of the hydrogen pipe, and the shape memory alloy ring 4 is provided on the outer periphery of the fitting portion. The following effects can be obtained. That is, since the shape memory alloy ring 4 is provided outside the pipe 11 and does not come into direct contact with hydrogen in the pipes 11 and 12, the shape memory alloy material is not subject to restrictions on corrosion resistance and strength against hydrogen. The degree of freedom of selection can be increased.

  When the hydrogen supply source 30 is filled with hydrogen, the shape memory alloy ring 5 is reduced in diameter at a predetermined transformation temperature or higher, so that the sealing performance between the pipes 11 and 12 is improved. In addition, the tightening allowance between the pipe 11 and the pipe 12 gradually increases as the pipe pressure and fluid temperature rise. Further, when hydrogen is released, the interference between the pipe 11 and the pipe 12 gradually decreases as the pipe pressure and fluid temperature decrease. That is, the interference can be reduced when the temperature is low and the gas pressure is low, and the interference can be selectively increased only when the temperature is high and the gas pressure is high.

  Therefore, a reliable sealing property can be obtained when necessary, and at the same time, the tightening margin is reduced at a low pressure, so that the occurrence of creep in the pipe 11, the pipe 12, and the seal material 5 can be suppressed.

  In addition, when applying the seal structure of the pipe joint part according to the present invention to, for example, an “autoclave-type joint” in which pipes are directly in metal contact, the sealing material 5 shown in the above embodiment is not necessary.

  Moreover, in the said embodiment, although shown about the case where it applied to the high voltage | pressure hydrogen piping of a fuel cell system, it cannot be overemphasized that the use of the seal structure of the piping joint part which concerns on this invention is not limited to this. It may be used for other than the fuel cell system, and can also be used for piping other than hydrogen piping.

It is the perspective view which fractured | ruptured and showed a part of piping joint shown as one Embodiment of this invention. (A) is a figure which showed the time-dependent change of gas temperature and pressure at the time of filling, (b) at the time of discharge | release. It is explanatory drawing which illustrates roughly the fuel cell system which concerns on one example of application of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Piping joint, 4 ... Shape memory alloy ring, 5 ... Sealing material, 11 ... Piping (1st fluid piping), 12 ... Piping (2nd fluid piping), 20 ... Fuel cell, 30 ... Hydrogen gas supply source 74 ... Fuel supply path

Claims (3)

A seal structure of a pipe joint portion that hermetically or / and liquid-tightly seals between a first fluid pipe and a second fluid pipe inserted at an end thereof,
A shape memory alloy ring that is extrapolated to the outside of the first fluid pipe and tightens the first fluid pipe to the second fluid pipe; the shape memory alloy ring has an inner diameter at a predetermined transformation temperature or higher; Is a seal structure of a pipe joint part, which is smaller than the inner diameter at a temperature lower than the transformation temperature.   The seal structure of the pipe joint part according to claim 1, wherein a seal material is provided between the first fluid pipe and the second fluid pipe.   The seal structure of a pipe joint part according to claim 1 or 2, wherein the first fluid pipe and the second fluid pipe are for high-pressure hydrogen.

Images