JP2014015983A - Seal structure of high-pressure gas container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure capable of surely preventing leakage of filled gas from a gap between a nozzle part of a high-pressure gas container and an accessory such as a connection pipe connected to the nozzle part.SOLUTION: The seal structure includes: a metal block 20 comprising a first truncated conical part 22, a column part 21 and a second truncated conical part 23 and having a through hole 24 on an axial center; and first and second rubber O-rings 25, 26 mounted around the column part 21 near the first truncated conical part 22 and near the second truncated conical part 23 respectively. A first recess 30 comprising an area of a tapered surface 31 and an area of a cylindrical surface 32 is formed on a nozzle part 4, a second recess 40 comprising an area of a tapered surface 41 and an area of a cylindrical surface 42 is formed on a connection pipe 5, the block 20 is stored in the first and second recesses 30, 40, the connection pipe 5 is pressed to the nozzle part 4, respective outer peripheral surfaces of the first and second truncated conical parts 22, 23 are brought into pressure-contact with the tapered surfaces 31, 41, and the respective first and second O-rings 25, 26 are brought into contact with the cylindrical surfaces 32, 42.

Description

  The present invention provides a high-pressure gas container that seals between a nozzle section corresponding to the mouth of a high-pressure gas container and accessories such as a connecting pipe and a stopcock that are connected to the nozzle, thereby preventing leakage of a filling gas. The present invention relates to a seal structure.

The high-pressure gas container is used to store gas (including liquefied gas) such as hydrogen (H ₂ ), oxygen (O ₂ ), and nitrogen (N ₂ ) in a high-pressure state. In general, a high-pressure gas container includes a cylindrical barrel portion, end plate portions formed at both ends of the barrel portion, and a nozzle portion protruding from one or both of the end plate portions. The nozzle part corresponds to the mouth of the high-pressure gas container, and the internal space of the high-pressure gas container opens to the outside through the nozzle part.

  In the case of a high-pressure gas container in which the nozzle part is provided on both of the end plate parts, one of the nozzle parts is provided with a connecting pipe to which piping can be attached as an accessory in order to fill and discharge gas. In order to close the opening, the stopper is continuously provided as an accessory in the other nozzle part. In the case of a high-pressure gas container in which the nozzle part is provided only on one of the end plate parts, a connecting pipe is connected to the nozzle part. As described above, since the accessory for the high-pressure gas container is connected to the nozzle part, a sealing structure that prevents the filling gas from leaking between the nozzle part and the accessory is indispensable (for example, , See Patent Document 1).

  FIG. 1 is a schematic view showing a conventional general seal structure, in which FIG. 1 (a) shows a sectional view of each member disassembled, and FIG. 1 (b) shows a section of each member assembled. The figure is shown. In the figure, the high-pressure gas container 1 has a nozzle part 4 protruding from an end plate part 3 formed at the end of the body part 2, and a connecting pipe 5 is connected to the nozzle part 4 as an accessory. Is illustrated. Further, the connection pipe 5 is fixed to the nozzle base 4 by using a cap nut 6 as an example.

  As shown in FIG. 1, in the conventional seal structure, an annular groove 5b is formed in the end surface 5a of the connecting pipe 5 facing the tip surface 4a of the nozzle base part 4, and a metal O-ring is formed in the annular groove 5b. 11 is inserted. The metal O-ring 11 is a hollow metal gasket in which a metal thin tube is formed into a ring shape, end surfaces thereof are welded, and then the surface is polished, and the surface is coated or plated as necessary.

  At the time of assembly, the connection pipe 5 provided with the metal O-ring 11 on the end face 5a is disposed adjacent to the tip of the nozzle base part 4 of the high-pressure gas container 1 and covered with the cap nut 6. Then, the cap nut 6 is screwed into the male screw 4 b formed on the outer peripheral surface of the nozzle pedestal 4, and the cap nut 6 is fastened to the nozzle pedestal 4, so that the connection pipe 5 has the metal O-ring 11 interposed therebetween. Then, it is pressed in the axial direction toward the nozzle part 4. As a result, the metal O-ring 11 is elastically deformed and is brought into pressure contact with the distal end surface 4 a of the nozzle pedestal portion 4 and is in pressure contact with the annular groove 5 b of the connection pipe 5.

  Thus, in the conventional seal structure, the metal O-ring 11 functions as a seal member, and the hermeticity is maintained by elastic contact between the metal O-ring 11 and the nozzle 4 and the connecting pipe 5. Leakage of the filling gas from the connection pipe 5 is prevented.

  The cap nut 6 is provided with a leak port 6a that leads to a gap between the tip surface 4a of the nozzle pedestal 4 and the end surface 5a of the connecting pipe 5. The leak port 6a is used for detecting leakage of the filling gas.

  By the way, the pressure specification of the gas filled in the high-pressure gas container has been generally about 10 to 20 MPa, and at most only about 40 MPa, but in recent years, the pressure specification is much more than 90 MPa. There was also. However, when the pressure of the filling gas is as high as 90 MPa, the sealing structure based on the elastic contact of the metal O-ring 11 as shown in FIG. 1 has insufficient sealing performance and cannot suppress the leakage of the filling gas. In particular, when a gas having a small molecule and high permeability such as hydrogen or helium (He) is filled, it is difficult to prevent leakage of the filling gas.

  For this reason, the present applicant has proposed a special seal structure that can ensure the sealing performance even when the pressure of the filling gas is high, as described in Patent Document 1.

  FIG. 2 is a schematic view showing a special seal structure described in Patent Document 1. FIG. 2 (a) shows a sectional view of each member in an exploded state, and FIG. 2 (b) shows the assembly of each member. FIG. 2C is an enlarged view of the main part of FIG. In the figure, the same reference numerals are attached to the same components as in FIG. 1, and a connecting pipe 5 is connected as an accessory to the nozzle part 4 of the high-pressure gas container 1, and the connection to the nozzle part 4 is performed. The fixing of the pipe 5 is exemplified by using a cap nut 6.

  In the seal structure shown in FIG. 2, a metal block 20 is interposed between the nozzle 4 and the connecting pipe 5 in place of the metal O-ring 11 shown in FIG. 1. Specifically, the metal block 20 includes a cylindrical portion 21, a first truncated cone portion 22 that tapers from one end of the cylindrical portion 21, and a second truncated cone portion that tapers from the other end of the cylindrical portion 21. 23 and has a through hole 24 along the axis. Moreover, in order to receive the metal block 20, the 1st recessed part 30 and the 2nd recessed part 40 are formed in the nozzle part 4 and the connecting pipe 5, respectively.

  The first recess 30 formed in the nozzle part 4 accommodates the entire first truncated cone part 22 of the metal block 20 and accommodates almost half of the cylindrical part 21 on the first truncated cone part 22 side. The first recess 30 has an area of a tapered surface 31, and the taper angle α 2 of this area coincides with the taper angle α 1 of the first truncated cone part 22 of the metal block 20. On the other hand, the second recess 40 formed in the connecting pipe 5 accommodates the entire second truncated cone part 23 of the metal block 20 and accommodates almost half of the cylindrical part 21 on the second truncated cone part 23 side. The second recess 40 has a region of a tapered surface 41, and the taper angle β 2 of this region coincides with the taper angle β 1 of the second truncated cone part 23 of the metal block 20.

  When assembling, the connecting pipe 5 is disposed adjacent to the tip of the nozzle 4 of the high-pressure gas container 1 and covered with a cap nut 6. At this time, the metal block 20 is inserted in the first recess 30 of the nozzle pedestal 4 and the second recess 40 of the connecting pipe 5. Then, when the cap nut 6 is fastened to the nozzle part 4, the connecting pipe 5 is pressed in the axial direction toward the nozzle part 4 with the metal block 20 interposed. As a result, the metal block 20 has the outer peripheral surface of the first truncated cone part 22 in pressure contact with the tapered surface 31 of the first recess 30, and the outer peripheral surface of the second truncated cone part 23 contacts the tapered surface 41 of the second recess 40. It is brought into a pressure contact state.

  As described above, in the seal structure shown in FIG. 2, the metal block 20 functions as a seal member, and at the same time the outer peripheral surface of the first truncated cone portion 22 and the tapered surface 31 of the first recess 30 are tapered and contact the metal surface. The outer peripheral surface of the second truncated cone portion 23 and the tapered surface 41 of the second recess 40 are in a tapered shape and contact with the metal surface, and the pressing force is concentrated on these contact surfaces, whereby the nozzle portion 4 and the connecting pipe 5 are Airtightness between the two is kept strong. Thereby, even if the pressure of the filling gas is high, leakage of the filling gas from between the nozzle 4 and the connecting pipe 5 is prevented.

JP 2011-196511 A

  In recent years, the pressure specification of the gas filled in the high-pressure gas container has been 90 MPa, and recently, a pressure specification exceeding that is required. Certainly, according to the seal structure by the metal surface contact of the metal block as shown in FIG. 2, when the pressure of the filling gas is up to 90 MPa, the leakage of the filling gas is prevented as described in Patent Document 1. It has been demonstrated that it can be prevented. However, it has not been verified when the pressure of the filling gas exceeds 90 MPa. Therefore, with the trend of increasing the pressure specification of the filling gas, further improvement of the sealing structure of the high-pressure gas container and establishment of the technology are strongly desired.

  The present invention has been made in view of the above circumstances, and even when the pressure of the filling gas is higher than 90 MPa, the nozzle base portion of the high-pressure gas container and the connecting pipe or stop connected thereto are provided. It is an object of the present invention to provide a seal structure that can reliably prevent leakage of a filling gas from an accessory such as a stopper.

  In order to achieve the above-mentioned object, the present inventor has made extensive studies by carrying out various tests on the premise of the sealing structure by the metal surface contact of the metal block as shown in FIG. As a result, in addition to the metal surface contact of the metal block similar to the seal structure shown in FIG. 2, if a rubber O-ring is attached to the cylindrical portion of the metal block and the elastic contact of this O-ring is utilized, It has been found that since a double seal of metal surface contact and elastic contact is formed, the sealing performance is improved and leakage of the filling gas can be surely prevented.

The present invention has been completed on the basis of such findings, and the gist thereof lies in the following high-pressure gas container seal structure. That is, the present invention is a seal structure between the nozzle part of the high-pressure gas container and the accessory connected to the nozzle part,
A cylindrical part, a first truncated cone part that tapers from one end of the cylindrical part, and a second truncated cone part that tapers from the other end of the cylindrical part, and has a through hole along the axis. Block of
A first O-ring made of rubber and provided near the first truncated cone part of the cylindrical part;
A second O-ring made of rubber and provided near the second truncated cone part of the cylindrical part,
The tube base portion includes a first concave portion including a region of a tapered surface that accommodates the entire first truncated cone portion and a region of a cylindrical surface that accommodates a portion of the columnar portion where the first O-ring is mounted. Formed,
The accessory includes a second concave portion including a tapered surface region that accommodates the entire second truncated cone portion and a cylindrical surface region that accommodates a portion of the columnar portion where the second O-ring is mounted. Formed,
The block is accommodated in the first concave portion of the nozzle base portion and the second concave portion of the accessory, and the accessory is pressed in the axial direction toward the nozzle base portion, thereby the first truncated cone portion. And the outer peripheral surface of the second truncated cone part is in pressure contact with the tapered surface of the second recess, and the first O-ring is in contact with the first recess. The second O-ring is in contact with the cylindrical surface of the second recess,
This is a high-pressure gas container sealing structure.

  In the above-described seal structure, it is preferable that the material of the block is extremely soft steel, pure iron, copper, aluminum, titanium or an alloy thereof, or stainless steel.

  In the above seal structure, it is preferable that the material of the first O-ring and the second O-ring is a synthetic rubber.

  In the above sealing structure, a first backup ring made of a resin harder than the first O-ring is provided around the cylindrical portion adjacent to the second truncated cone portion side of the first O-ring, and the second O-ring is mounted. It is preferable that a second back-up ring made of a resin harder than the second O-ring is provided adjacent to the first truncated cone part side of the ring.

  In the above seal structure, the surface roughness of the outer peripheral surface of each of the first truncated cone portion and the second truncated cone portion, and the tapered surface of each of the first recessed portion and the second recessed portion is an arithmetic average roughness. The thickness (Ra) is preferably 1.6 μm or less.

  In the above sealing structure, the processing tolerance of the taper angle of each of the first truncated cone part and the second truncated cone part is set to −2 ° / + 0 °, and the tapered surface of each of the first recessed part and the second recessed part. It is preferable to set the processing tolerance of the taper angle in the region of −0 ° / + 2 °.

  According to the seal structure of the present invention, first, the metal block functions as a seal member by metal surface contact, and in addition, the first and second O-rings function as further seal members by elastic contact, so that the seal performance is improved. Even when the pressure of the filling gas is higher than 90 MPa, leakage of the filling gas can be reliably prevented.

It is a schematic diagram which shows the conventional general seal structure, The figure (a) shows sectional drawing of the state which decomposed | disassembled each member, The figure (b) shows sectional drawing of the state which assembled | attached each member. It is a schematic diagram which shows the special seal structure described in patent document 1, The figure (a) shows sectional drawing of the state which decomposed | disassembled each member, The figure (b) is a cross section of the state which assembled | attached each member. The figure (c) shows the principal part enlarged view of the figure (a). It is a schematic diagram which shows the seal structure of 1st Embodiment of this invention, The figure (a) shows sectional drawing of the state which decomposed | disassembled each member, The figure (b) is sectional drawing of the state which assembled | attached each member. The figure (c) shows the principal part enlarged view of the figure (a). It is a schematic diagram which shows the seal structure of 2nd Embodiment of this invention, The figure (a) shows sectional drawing of the state which decomposed | disassembled each member, The figure (b) is sectional drawing of the state which assembled | attached each member. Indicates. It is a schematic diagram which shows the seal structure of 3rd Embodiment of this invention, The figure (a) shows sectional drawing of the state which decomposed | disassembled each member, The figure (b) is sectional drawing of the state which assembled | attached each member. Indicates. It is a figure which shows the relationship between the pressure of a filling gas, and the leak occurrence rate as a test result of an Example.

  Below, the embodiment is explained in full detail about the sealing structure of the high-pressure gas container of the present invention.

<First Embodiment>
FIG. 3 is a schematic view showing a seal structure according to the first embodiment of the present invention. FIG. 3 (a) shows a sectional view of each member in an exploded state, and FIG. 3 (b) shows that the members are assembled. The sectional view of a state is shown, and the figure (c) shows the principal part enlarged view of the figure (a). The seal structure of the first embodiment shown in the figure is based on the structure of the seal structure shown in FIG. 2, and the same reference numerals are given to the same elements as those in FIG. .

  As shown in FIG. 3, in the seal structure of the first embodiment, a connecting pipe 5 is connected as an accessory to the nozzle 4 of the high-pressure gas container 1, and the connecting pipe 5 is fixed to the nozzle 4. A cap nut 6 is used. Similar to the seal structure shown in FIG. 2, a metal block 20 including a columnar part 21, a first truncated cone part 22, and a second truncated cone part 23 is interposed between the nozzle part 4 and the connecting pipe 5. ing. The first truncated cone part 22 is connected in a tapered manner from one end of the cylindrical part 21, and the second truncated cone part 23 is connected in a tapered form from the other end of the cylindrical part 21. A through hole 24 is formed in the metal block 20 along the axial center across the first truncated cone part 22, the cylindrical part 21 and the second truncated cone part 23.

  As the material of the metal block 20, it is possible to employ extremely soft steel, pure iron, copper, aluminum, titanium or their alloys, or stainless steel.

  Further, a first circumferential groove 21a is formed on the outer peripheral surface of the cylindrical portion 21 in a circumferential direction at a position near the first truncated cone portion 22, and a first circumferential groove is formed at a position near the second truncated cone portion 23. Two circumferential grooves 21b are formed. A first O-ring 25 made of rubber that can be elastically deformed is fitted into the first circumferential groove 21a, and a second O-ring 26 made of rubber that can also be elastically deformed is fitted into the second circumferential groove 21b. . Synthetic rubber can be adopted as the material of the first and second O-rings 25 and 26, and nitrile rubber or the like generally called NBR is used.

  Furthermore, in the first embodiment, the first circumferential groove 21 a is adjacent to the second truncated cone part 23 side (the opposite side to the first truncated cone part 22 side) of the first O ring 25, and the first O ring. A first backup ring 27 made of resin harder than 25 is fitted. The second circumferential groove 21b is adjacent to the first truncated cone part 22 side of the second O ring 26 (on the opposite side to the second truncated cone part 23 side) and is made of a resin made of a resin harder than the second O ring 26. 2 A backup ring 28 is fitted. The first and second backup rings 27 and 28 suppress excessive deformation of the first and second O-rings 25 and 26, respectively, and from the first and second circumferential grooves 21a and 21b to the first and second O-rings 25 and 25, respectively. It plays the role which prevents that 26 falls out. As the material of the first and second backup rings 27 and 28, hard fluororesin can be adopted, and generally polytetrafluoroethylene (PTFE) or the like is used.

  As described above, the cylindrical portion 21 is provided with the first O-ring 25 and the first backup ring 27 near the first truncated cone portion 22, and the second O-ring 26 and the second backup ring near the second truncated cone portion 23. 28 is ringed.

  In addition, in order to receive the metal block 20 having the first and second O-rings 25 and 26 and the first and second backup rings 27 and 28 in the nozzle base part 4 and the connecting pipe 5, respectively, A recess 30 and a second recess 40 are formed.

  The first recess 30 formed in the tube base part 4 is an area of the tapered surface 31 that accommodates the entire first truncated cone part 22 of the metal block 20 and substantially half of the cylindrical part 21 on the first truncated cone part 22 side. It consists of the area | region of the cylindrical surface 32 which accommodates. The taper angle α <b> 2 of the tapered surface 31 of the first recess 30 matches the taper angle α <b> 1 of the first truncated cone part 22 of the metal block 20. The portion of the columnar portion 21 where the first O-ring 25 is mounted is accommodated in the region of the cylindrical surface 32 of the first recess 30.

  On the other hand, the second concave portion 40 formed in the connecting pipe 5 is substantially the region of the tapered surface 41 that accommodates the entire second truncated cone portion 23 of the metal block 20 and the second truncated cone portion 23 side of the cylindrical portion 21. It consists of a region of a cylindrical surface 42 that accommodates half. The taper angle β2 of the taper surface 41 of the second recess 40 coincides with the taper angle β1 of the second truncated cone part 23 of the metal block 20. The portion of the cylindrical portion 21 where the second O-ring 26 is mounted is accommodated in the region of the cylindrical surface 42 of the second recess 40.

  When assembling, the connecting pipe 5 is disposed adjacent to the tip of the nozzle 4 of the high-pressure gas container 1 and covered with a cap nut 6. At this time, the metal block 20 provided with the first and second O-rings 25 and 26 and the first and second backup rings 27 and 28 in the first recess 30 of the nozzle 4 and the second recess 40 of the connecting pipe 5. Is in the inserted state. Then, when the cap nut 6 is fastened to the nozzle part 4, the connecting pipe 5 is pressed in the axial direction toward the nozzle part 4 with the metal block 20 interposed.

  As a result, the metal block 20 has the outer peripheral surface of the first truncated cone part 22 in pressure contact with the tapered surface 31 of the first recess 30, and the outer peripheral surface of the second truncated cone part 23 contacts the tapered surface 41 of the second recess 40. It is brought into a pressure contact state. At the same time, the first O-ring 25 comes into contact with the cylindrical surface 32 of the first recess 30 by elastic deformation, and the second O-ring 26 comes into contact with the cylindrical surface 42 of the second recess 40 by elastic deformation.

  According to such a seal structure of the first embodiment, first, the metal block 20 functions as a seal member, and the outer peripheral surface of the first truncated cone portion 22 and the tapered surface 31 of the first recess 30 are tapered and have a metal surface. Simultaneously with the contact, the outer peripheral surface of the second truncated cone part 23 and the tapered surface 41 of the second recess 40 are in a tapered shape and contact with the metal surface, and the pressing force is concentrated on these contact surfaces, thereby connecting to the nozzle part 4. The airtightness between the tube 5 is kept strong. In addition, the first and second O-rings 25 and 26 function as further sealing members, and elastic contact between the first O-ring 25 and the nozzle 4 and the metal block 20, and the second O-ring 26 and the connecting pipe 5 and metal. Due to the elastic contact with the block 20, airtightness is maintained even on the downstream side of the metal surface contact. For this reason, since a double seal of metal surface contact and elastic contact is formed, the sealing performance is improved, and even if the pressure of the filling gas exceeds 90 MPa, the nozzle 4 and the connecting pipe 5 Leakage of the filling gas from between the two can be reliably prevented.

  The material of the high-pressure gas container 1 is not particularly limited, but is low such as chromium molybdenum steel (eg, JIS standard SCM435) and nickel chrome molybdenum steel (eg, JIS standard SNCM439) having excellent pressure resistance and corrosion resistance. Alloy steel can be adopted. Also, the material of the metal block 20 and the connecting pipe 5 is not particularly limited. However, when hydrogen is used as the filling gas, stainless steel (eg, JIS standard SUS316L) that is less affected by hydrogen embrittlement can be used. .

  Here, in order to prevent leakage of the filling gas by contact with the metal surface, the first and second truncated cones are caused by the axial pressing force as the connecting pipe 5 is pressed in the axial direction toward the nozzle 4. The surface pressure (hereinafter referred to as “surface contact force”) acting at right angles to the contact surfaces of the outer peripheral surfaces of the portions 22 and 23 and the tapered surfaces 31 and 41 of the first and second recesses 30 and 40 is at least filled gas. The pressure must be exceeded. Since the pressing force of the connecting pipe 5 depends on the tightening torque of the cap nut 6, the surface contact force can be adjusted by adjusting the tightening torque of the cap nut 6. The taper angles α1 and β1 of the first and second truncated cone portions 22 and 23 of the metal block 20 (taper angles α2 and β2 of the taper surfaces 31 and 41 of the first and second concave portions 30 and 40) are as follows: The pressure is appropriately set according to the materials of the high-pressure gas container 1, the metal block 20 and the connection pipe 5.

  However, when the material of the high-pressure gas container 1 (base 4) and the material of the connecting pipe 5 are different, and the material strength of the high-pressure gas container 1 and the material strength of the connecting pipe 5 are different, the lower the material strength, the more The amount increases and the filling gas is likely to leak. For this reason, in order to complement the surface contact force with the lower material strength, it is desirable that the taper angle with the lower material strength be larger than the taper angle with the higher material strength.

  Specifically, when the material strength of the tube base part 4 is higher than the material strength of the connection pipe 5, the taper angle α1 of the first truncated cone part 22 on the side with the higher material strength and the taper surface 31 of the first recess 30. The taper angle α2 of the region is set to be smaller than the taper angle β1 of the second truncated cone portion 23 on the low material strength side and the taper angle β2 of the region of the tapered surface 41 of the second recess 40. For example, the former taper angle is 30 ° and the latter taper angle is 45 °. On the contrary, when the material strength of the nozzle 4 is lower than the material strength of the connecting pipe 5, the taper angle α 1 of the first truncated cone 22 on the side having a lower material strength and the tapered surface 31 of the first recess 30. Is made larger than the taper angle β1 of the second truncated cone portion 23 on the side having a higher material strength and the taper angle β2 of the region of the tapered surface 41 of the second recess 40. For example, the former taper angle is 45 °, and the latter angle is 30 °.

  The surface roughness of the outer peripheral surfaces of the first and second truncated cone portions 22 and 23 and the tapered surfaces 31 and 41 of the first and second recesses 30 and 40 are arithmetic averages based on JIS standard B0601. The roughness (Ra) is preferably 1.6 μm or less. More preferably, it is 0.8 μm or less. This is because each surface described above is a contact surface in contact with a metal surface, and if the surface roughness is too large, the filling gas permeates and leaks.

  Further, the processing tolerances of the taper angles α1 and β1 of the first and second truncated cone parts 22 and 23 are set to −2 ° / + 0 °, respectively, and regions of the tapered surfaces 31 and 41 of the first and second recesses 30 and 40, respectively. The machining tolerances of the taper angles α2 and β2 are preferably set to −0 ° / + 2 °. That is, in the state before the assembly, the taper angle α1 of the first truncated cone part 22 is the same as or smaller than the taper angle α2 of the region of the tapered surface 31 of the first recess 30 to obtain the second truncated cone. The taper angle β1 of the portion 23 is the same as or smaller than the taper angle β2 of the region of the tapered surface 41 of the second recess 40. If the taper angles α1 and β1 of the first and second truncated cone parts 22 and 23 are larger, the first and second truncated cone parts 22 and 23 are not inserted to the back of the first and second recesses 30 and 40. This is because the metal surface contact between the outer peripheral surfaces of the first and second truncated cone portions 22 and 23 and the tapered surfaces 31 and 41 of the first and second recesses 30 and 40 becomes insufficient.

Second Embodiment
FIG. 4 is a schematic view showing a seal structure according to a second embodiment of the present invention, where FIG. 4 (a) shows a sectional view of each member in an exploded state, and FIG. 4 (b) shows that the members are assembled. A sectional view of the state is shown. The seal structure of the second embodiment shown in the figure is a modification of the structure of the seal structure of the first embodiment shown in FIG.

  As shown in FIG. 4, in the seal structure of the second embodiment, a stopcock 7 is applied as an accessory connected to the nozzle base part 4 of the high-pressure gas container 1 instead of the connecting pipe 5 shown in FIG. doing. A second recess 40 similar to that of the first embodiment is formed in the stopper plug 7. Thereby, also when using the stopper plug 7 as an accessory, leakage of the filling gas from between the nozzle part 4 and the stopper plug 7 can be reliably prevented. When the stopcock 7 is used, the metal block 20 may not have the through-hole 24 formed along the axis extending over the first truncated cone part 22, the columnar part 21, and the second truncated cone part 23. Absent.

<Third Embodiment>
FIG. 5 is a schematic view showing a seal structure according to a third embodiment of the present invention. FIG. 5 (a) shows a sectional view of each member in an exploded state, and FIG. 5 (b) shows that the members are assembled. A sectional view of the state is shown. The seal structure of the third embodiment shown in the figure is a modification of the structure of the seal structure of the first embodiment shown in FIG.

  As shown in FIG. 5, in the seal structure of the third embodiment, a flange type is applied instead of the cap nut 6 shown in FIG. 3 in order to fix the connection pipe 5 to the nozzle base part 4. That is, the flange 8 is attached to the male screw 4 b of the nozzle 4, the holding flange 9 is attached to the connecting pipe 5, and the flange 8 and the holding flange 9 are fastened by the bolt 10. As described above, even in the case of the flange type, the connection pipe 5 is pressed in the axial direction toward the nozzle pedestal portion 4 with the metal block 20 interposed therebetween, so that the same effect as in the first embodiment can be obtained.

  However, in the seal structure of the third embodiment, a stopper may be used in the same manner as in the second embodiment, instead of the connecting pipe 5 shown in FIG. In this case, a pressing flange is attached to the stopper.

  In order to confirm the effect of the seal structure of the present invention, the following airtight test was conducted.

[Test method]
In the example of the present invention, an airtight test using hydrogen gas having high permeability as the filling gas was performed. For this reason, the nozzle part is cut out from the high-pressure gas container, and the metal surface contact of the metal block and the first one are connected to the tip of the nozzle part by a cap nut as shown in FIG. 4 (b). A specimen having a seal structure by elastic contact of the second O-ring was used as a test specimen. A gas supply pipe is connected to the rear end of the base of the test body, and after connecting a pump for pumping hydrogen gas and a pressure gauge for measuring the pressure of the hydrogen gas to the gas supply pipe, It was stored in a test pressure chamber and isolated from the outside air.

  Then, one test specimen was prepared, and hydrogen gas was fed into the test specimen in stages until the pressure reached 105 MPa. Every time the pressure increased by about 10 MPa, the test specimen (between the nozzle and stopper) The presence or absence of hydrogen gas leakage was investigated. Judgment of the presence or absence of leakage of hydrogen gas was performed by detecting hydrogen gas in the pressure-resistant chamber by gas chromatography. The reason why the test is carried out in the pressure resistant chamber in this manner is for safety reasons because hydrogen gas with a risk of explosion is used.

  In the test of the example of the present invention, the material of the nozzle part was SCM435, and the material of the stopper and the metal block was SUS316L. Comparing SCM435 and SUS316L, the material strength of SCM435 is higher. Therefore, the taper angle of the first truncated cone portion and the first recess on the side of the tube base portion where the material strength is high is 30 °, and the stopper side where the material strength is low The taper angle of the second truncated cone part and the second concave part was 45 °, which was larger than that. The material of the first and second O-rings was NBR, and the material of the first and second backup rings was PTFE.

  In the comparative example, an airtight test using nonflammable nitrogen gas as a filling gas was performed. For this reason, a high-pressure gas container in which the nozzle part is provided on both of the end plate parts is used, and at the tip of one of the nozzle parts, a connecting pipe is continuously provided by a cap nut as shown in FIG. A specimen having a seal structure in which a stopper is connected to the tip of the nozzle base by a cap nut and elastic contact with a metal O-ring was used as a test specimen. A gas supply pipe was connected to the connection pipe of the test body, and a pump for feeding nitrogen gas and a pressure gauge for measuring the pressure of the nitrogen gas were connected to the gas supply pipe.

  In the test of the comparative example, the material of the nozzle (high pressure gas container) was SCM435 or SNCM439, and the material of the connecting pipe, stopper, and metal O-ring was SUS316L. Two types of high-pressure gas containers having a capacity of 60 L (liter) (made of SNCM439 steel) and 100 L (made of SCM435 steel) were used, the former being Comparative Example 1 and the latter being Comparative Example 2.

  In Comparative Example 1 (60 L container), 11 test bodies were prepared, and nitrogen gas was fed into each test body in stages until the pressure reached 90 MPa. In Comparative Example 2 (100 L container), Test specimens are prepared, and nitrogen gas is fed in stages to each specimen until a pressure of 72 MPa is reached, and each time the pressure rises by about 10 MPa, nitrogen gas from the specimen (between the tube base and the connecting pipe) is supplied. The presence or absence of leakage was investigated. Judgment of the presence or absence of nitrogen gas leakage was performed by injecting the detection liquid into leak ports provided at two locations on the cap nut and confirming the presence or absence of bubbles.

[Evaluation method]
The inventive example, Comparative Example 1 and Comparative Example 2 were all evaluated by calculating the gas leakage occurrence rate. The gas leakage occurrence rate in the example of the present invention is displayed as 100 (%) when gas leakage is recognized and 0 (%) when gas leakage is not recognized for one specimen. On the other hand, the gas leakage occurrence rate in Comparative Example 1 was calculated by dividing the number of leak ports in which gas leakage was observed for a total of 22 leak ports of 11 specimens by the total number of leak ports (% ) Is displayed. Similarly, the gas leak occurrence rate in Comparative Example 2 is a percentage of the total number of leak ports in five test specimens divided by the total number of leak ports, divided by the total number of leak ports. %).

[Test results]
FIG. 6 is a diagram showing the relationship between the pressure of the filling gas and the leakage occurrence rate as a test result of the example. As shown in the figure, in the present invention example of the seal structure by the metal surface contact of the metal block and the elastic contact of the first and second O-rings, even if the filling gas is highly permeable hydrogen gas, the pressure is 90 MPa. No leakage occurred at a pressure exceeding 105 MPa. On the other hand, in Comparative Examples 1 and 2 of the seal structure by the elastic contact of the metal O-ring, the occurrence of leakage was recognized when the filling gas pressure exceeded 50 MPa.

  The seal structure of the present invention is useful for a high-pressure gas container in which the pressure of the filling gas exceeds 90 MPa.

1: High pressure gas container, 2: Body, 3: End plate,
4: nozzle section, 4a: tip surface, 4b: male screw,
5: connecting pipe, 5a: end face, 5b: annular groove,
6: Cap nut, 6a: Leak port, 7: Stopcock,
8: Flange, 9: Pressing flange, 10: Bolt,
11: Metal O-ring,
20: metal block, 21: cylindrical part,
21a: first circumferential groove, 21b: second circumferential groove,
22: first truncated cone part, 23: second truncated cone part,
24: Through hole, 25: First O-ring, 26: Second O-ring,
27: First backup ring, 28: Second backup ring,
30: 1st recessed part, 31: The taper surface of a 1st recessed part, 32: The cylindrical surface of a 1st recessed part,
40: 2nd recessed part, 41: Tapered surface of 2nd recessed part, 42: Cylindrical surface of 2nd recessed part,
α1: taper angle of the first truncated cone part, β1: taper angle of the second truncated cone part,
α2: Angle of the first concave tapered surface, β2: Angle of the second concave tapered surface

Claims (6)

A seal structure between a nozzle part of a high-pressure gas container and an accessory connected to the nozzle part,
A cylindrical part, a first truncated cone part that tapers from one end of the cylindrical part, and a second truncated cone part that tapers from the other end of the cylindrical part, and has a through hole along the axis. Block of
A first O-ring made of rubber and provided near the first truncated cone part of the cylindrical part;
A second O-ring made of rubber and provided near the second truncated cone part of the cylindrical part,
The tube base portion includes a first concave portion including a region of a tapered surface that accommodates the entire first truncated cone portion and a region of a cylindrical surface that accommodates a portion of the columnar portion where the first O-ring is mounted. Formed,
The accessory includes a second concave portion including a tapered surface region that accommodates the entire second truncated cone portion and a cylindrical surface region that accommodates a portion of the columnar portion where the second O-ring is mounted. Formed,
The block is accommodated in the first concave portion of the nozzle base portion and the second concave portion of the accessory, and the accessory is pressed in the axial direction toward the nozzle base portion, thereby the first truncated cone portion. And the outer peripheral surface of the second truncated cone part is in pressure contact with the tapered surface of the second recess, and the first O-ring is in contact with the first recess. The second O-ring is in contact with the cylindrical surface of the second recess,
A high pressure gas container sealing structure characterized by the above. The material of the block is extremely soft steel, pure iron, copper, aluminum, titanium or an alloy thereof, or stainless steel,
The high-pressure gas container sealing structure according to claim 1. The material of the first O-ring and the second O-ring is a synthetic rubber;
The seal structure for a high-pressure gas container according to claim 1 or 2. A first back-up ring made of resin harder than the first O-ring is provided adjacent to the cylindrical portion adjacent to the second truncated cone portion of the first O-ring, and the first cone of the second O-ring A second backup ring made of resin harder than the second O-ring is mounted adjacent to the base side,
The seal structure for a high-pressure gas container according to any one of claims 1 to 3. The surface roughness of the outer peripheral surface of each of the first truncated cone part and the second truncated cone part, and the tapered surface of each of the first recessed part and the second recessed part is 1.6 μm in terms of arithmetic average roughness (Ra). That
The seal structure for a high-pressure gas container according to any one of claims 1 to 4. The processing tolerance of the taper angle of each of the first truncated cone part and the second truncated cone part is set to −2 ° / + 0 °, and the taper angle of the region of the tapered surface of each of the first recessed part and the second recessed part is processed. The tolerance is -0 ° / + 2 °,
The seal structure for a high-pressure gas container according to any one of claims 1 to 5.

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