JP4616896B2 - High-pressure hydrogen gas seal - Google Patents

Description

  The present invention relates to a seal for sealing high-pressure hydrogen gas.

  Recently, research and development of hydrogen gas fuel cell vehicles has progressed, but valves such as regulator solenoid valves are used in the middle of piping for sending high-pressure hydrogen gas for fuel. Conventionally, no suitable sealing seal has been available.

  As shown in FIG. 9, a rubber O-ring 41 is used as a seal for a general fluid valve, and a concave circumferential groove 43 formed integrally with a spool (shaft) 42 is a so-called integral groove. As shown by the two-dot chain line, the O-ring 41 was elastically expanded and installed beyond the basic diameter end 44. Reference numeral 45 denotes a valve main body (also referred to as a housing or a body), and the O-ring 41 comes into contact (sliding contact) with the inner peripheral surface of the hole 45a.

The reason for the above-mentioned integral groove is that when the split groove structure is adopted, the end portion of the basic diameter in FIG. 9 is fixed as a separate part with a screw, bolt, snap ring, etc. This is because there is a problem such as an increase in the volume of the kind.
However, if the fluid to be sealed is the hydrogen gas fuel cell vehicle, the pressure becomes high, for example, 50 MPa, and there is a pressure fluctuation when the valves are turned on and off. There was a fear.
Also, the metal O-ring cannot be mounted in the integral groove structure because the diameter cannot be expanded (stretched) as shown by the two-dot chain line in FIG. Further, since the spool (shaft) 42 reciprocates in the axial direction (small size), wear of the hole 45a and wear of the metal O-ring are remarkably unsuitable for use.

  Therefore, the present invention can be applied to valves such as a regulator solenoid valve for controlling the pressure of the high-pressure hydrogen gas of the automobile fuel as described above, and the conventional blister is not generated, and the outside of the high-pressure hydrogen gas is not generated. It is an object to provide a seal with little leakage and a long life.

A seal for high-pressure hydrogen gas according to the present invention is provided in a resin seal body that is fitted on a shaft having an opening groove portion formed in one axial direction by an inner lip portion and an outer lip portion, and is fitted in the opening groove portion. In the high-pressure hydrogen gas seal comprising the above-described spring, the material of the seal body is modified PTFE, and the thickness of the bottom wall portion on the back side of the opening groove portion of the seal body is defined as the seal body. Is set to 35% to 50% of the axial direction dimension, and the sealing projection of the inner lip portion is formed to contact the shaft in a strip shape, and the cross-sectional shape of the spring is U-shaped, Provided in the opening groove so that the opening end faces in one axial direction, the opening end of the spring contacts the inner and outer lip portions and elastically presses to open the opening groove. Axial-direction acting position that elastically urges and seals the inner lip At least a part of the protrusion is made to coincide with the axial direction position of the top of the sealing protrusion of the outer lip portion.

The present invention has the following remarkable effects by the above-described configuration.
The high-pressure hydrogen gas seal according to the present invention can sufficiently suppress gas permeation through the bottom wall even when the pressure of the hydrogen gas as the sealed fluid is as high as 50 MPa, for example. In addition, the seal body is prevented from becoming unnecessarily large.
Further, the spring urging force of the spring is effectively transmitted to the sealing projection. As a result, the contact surface pressure with respect to the outer peripheral surface of the shaft and the inner peripheral surface of the housing hole is sufficiently increased, and the sealing performance is reliably exhibited.
In addition, the amount of leakage is further reduced as compared with PTFE containing filler. Moreover, for example, it can be applied to high-pressure hydrogen gas as high as 50 MPa, leakage is minimized, and the creep resistance is excellent.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
1 to 3 show a reference example having a close relation with the present invention, FIG. 2 is a cross-sectional view of the seal S in a free state, FIG. 3 is a cross-sectional view illustrating a mounting (use) portion, and FIG. FIG. 5 is a diagram for explaining a positional relationship and a dimensional relationship between the seal S and a mounting (use) place.
The seal S has an inner lip portion 1 and an outer lip portion 2, and a resin seal main body 4 having a substantially U-shaped cross section in which an opening groove portion 3 is formed in one axial direction by the inner and outer lip portions 1 and 2. , And a spring 5 having a substantially U-shaped cross section provided in the opening groove 3.

Between the regulator solenoid valve that controls the high-pressure hydrogen gas, the hole 7 of the housing (body) 6 of valves such as a switching valve and a flow control valve, and the shaft 8 such as the spool and valve stem (valve body) The seal S is mounted in the storage recess 9 formed in the above.
The shaft 8 is formed with a stepped surface 10 that forms a deep bottom surface on the low-pressure side of the housing recess 9, and a large-diameter portion (land portion) 11 having an outer diameter D ₀ slightly smaller than the hole portion 7. A small-diameter portion 12 with which the inner lip portion 1 is slidably contacted (contacted) is defined by the stepped surface 10.

A small protruding strip 13 for retaining the seal is integrated with the outer peripheral surface 8 a of the shaft 8 at a position away from the stepped surface 10 by an axial direction dimension H ₀ slightly larger than the axial direction dimension H of the seal S. To form. Specifically, the small ridge 13 has a substantially unequal triangular shape integrally formed in a protruding manner on the outer peripheral surface of the small diameter portion 12, and the tip surface 14 side of the small diameter portion 12 has a gently tapered surface ( (Inclined surface) 13a, and the stepped surface 10 side is a locking surface 13b in a direction substantially perpendicular to the axis 15 of the shaft 8 or a steeply inclined surface or a small round shape.

The axial center direction dimension H ₀ indicates a distance dimension from the locking surface 13b to the stepped surface 10. Then, the axial dimension H ₀ is set so that the following expression (1) is satisfied.
1.10 × H ≦ H ₀ ≦ 1.25 × H (1)
In other words, the seal S is loose with respect to the movement of the shaft 8 in the axial direction and has a margin.

Then, the outer diameter D ₁₃ of the small protrusion 13 for preventing the seal from coming off is set to 104% to 125% of the outer diameter D ₁₂ where the shaft 8 forms the inner peripheral surface of the housing recess 9. In particular, 105% to 110% is desirable.
This can be expressed by the following equations (2) and (3).
1.04 × D ₁₂ ≦ D ₁₃ ≦ 1.25 × D ₁₂ (2)
Preferably
1.05 x D ₁₂ ≤ D ₁₃ ≤ 1.10 x D ₁₂ (3)
In addition, the site | part in which the above-mentioned axis | shaft 8 forms the internal peripheral surface of the storage recess 9 specifically, the small diameter part 12 is equivalent.

  By the way, the seal S will be described in detail. The material of the seal body 4 is preferably modified PTFE, and the material of the spring 5 is preferably a Ni—Cr corrosion resistant alloy.

In the present invention, modified PTFE means a co-weight of tetrafluoroethylene and perfluoro (alkyl vinyl ether). As an example of such modified PTFE, a copolymer of at least one perfluoro (alkyl vinyl ether) represented by the general formula R—O—CF═CF ₂ and tetrafluoroethylene is used. Further, as perfluoro (alkyl vinyl ether), those in which R in the above formula is a C 3-4 perfluoroalkyl group, such as perfluoro (propyl vinyl ether), perfluoro (butyl vinyl ether) and the like are preferable. Further, it is preferable to contain 0.1 to 10% by weight, preferably 0.5 to 5% by weight of perfluoro (alkyl vinyl ether).

  And the material which does not mix a filler is desirable. The reason is that when the pressure of high-pressure hydrogen gas such as 50 MPa is applied, the surfaces of the inner and outer lip portions 1 and 2 become rough (fine irregularities occur) in the PTFE containing filler, and the outer peripheral surface of the shaft 8 and the hole 7 The high-pressure hydrogen gas is likely to leak from a portion (contact surface) that contacts the inner peripheral surface.

  As a Ni-Cr corrosion resistant alloy applied to the spring 5, a corrosion resistant alloy Inconel (registered trademark) of Ni 76%, Cr 16% and Fe 8% is excellent in terms of corrosion resistance to hydrogen gas.

The inner lip portion 1 has a sealing projection 16 and a locking projection 17 that can be locked to the locking surface 13 b of the small protrusion 13 of the small diameter portion 12 of the shaft 8.
The locking protrusion 17 is a sloped surface that gradually expands toward the thick walled bottom wall 19 side of the seal body 4 and an axially orthogonal surface formed in a continuous flat surface with the tip surface 18 of the inner lip portion 1. 20 is a triangular mountain type.

  The sealing projection 16 has a triangular mountain shape having an axial orthogonal surface 21 and a sloped surface 22 that gradually increases in diameter toward the bottom wall portion 19 side. Both protrusions 16 and 17 are set to have the same inner diameter, and the protrusion 17 near the distal end face 18 is loosely mounted in the housing recess 9 with sufficient margin in the axial direction as shown in FIG. Thus, when the seal main body 4 is about to come out, the seal main body 4 is locked to the locking surface 13b of the small protrusion 13 for preventing the seal from being removed from the shaft 8 (small diameter portion 12), and is securely prevented from coming off. In addition, the locking projections 17 provide a sealing (sealing) action in the same manner as the adjacent sealing projections 16. In other words, the seal body 4 includes a double seal lip (seal protrusion) on the inner peripheral surface side.

  On the other hand, the outer lip portion 2 has a low-triangular sealing projection 23 having a gently inclined surface from the apex to the distal end and the proximal direction. As can be seen from FIG. 2, the sealing protrusion 23 on the outer lip portion 2 side and the sealing protrusion 16 on the inner lip portion 1 side are disposed on the same plane orthogonal to the axis 15, and the opening groove portion 3. The axially acting position of the spring 5 that elastically urges the opening in the opening direction coincides with the axial direction position of the top portions (vertices) of the seal projections 16 and 23.

The spring 5 has a U-shaped cross section, and is incorporated in the opening groove 3 of the seal body 4 so as to be open to the tip side --- the high-pressure hydrogen gas storage space 24 side--. The axial direction position where the open end portions 25, 25 having a U-shaped cross section come into contact with the inner and outer lip portions 1, 2 and elastically press is the axial direction acting position. On one orthogonal plane, the operating position of the spring 5 (open end portions 25, 25) and the top portions (vertices) of the inner and outer sealing projections 16, 23 are arranged.
As a result, the elastic urging force of the spring 5 is directly and effectively applied to the contact surface pressure of the sealing protrusions 16 and 23 on the mating member-the outer peripheral surface of the shaft 8 and the inner peripheral surface of the hole 7. Can contribute to increase, and exhibits high sealing performance.

Further, as shown in FIGS. 1 and 2, the thickness T of the bottom wall portion 19 of the seal body 4 corresponding to (facing to) the stepped surface 10 of the shaft 8 is set to the axial dimension H of the seal body 4. Set 35% to 50% thick enough (than other parts). That is, the following equation is set.
0.35 x H ≤ T ≤ 0.50 x H (4)
In the above formula (4), if it is less than the lower limit value, the permeation amount of gas (high-pressure hydrogen gas) increases rapidly. On the other hand, when the upper limit is exceeded, unnecessary portions as a seal increase, and material is wasted.

At a reference example of FIG. 1-3, the outer diameter D ₁₃ is the seal retaining the small ridges 13 (3) as in equation because it is set sufficiently small, the inner lip portion of the seal body 4 1 is lightly elastically deformed and can be easily mounted in the storage recess 9, and the inner lip 1 in the storage recess 9, especially the sealing protrusion 16 and the locking protrusion 17, is elastically restored. Therefore, a sufficient contact surface pressure for sealing can be obtained without impairing the force, and excellent sealing performance can be exhibited.
At this time, the gentle taper surface (inclined surface) 13a makes it possible for the seal S to exceed the small ridges 13 more lightly and easily. Further, since the locking surface 13b has a substantially planar shape orthogonal to the shaft center 15, the locking projection 17 is securely locked by the locking projection 17 so that the seal S is removed from the storage recess 9. There is an advantage that it does not come out (does not jump out).

In the expression (3), if the outer diameter D ₁₃ is less than the lower limit value, the small ridges 13 are overcome by the use conditions in a large number of seals S and come out of the storage recess 9. Things suddenly increase. On the contrary, if the upper limit is exceeded, the seal protrusion 16 of the inner lip portion 1 is damaged by the small protrusion 13 when the seal is mounted, or the seal protrusion 16 is plastically deformed in the diameter increasing direction with the above-mentioned resin material. As a result, the amount of high-pressure hydrogen gas leakage increases rapidly.

Next, FIGS. 4, 5 and 6 show the each other Example.
4 and 5, the seal projection 26 of the inner lip portion 1 is a low triangular mountain shape similar to the seal projection 23 of the outer lip portion 2 (as is apparent when compared with FIG. 2). This is a case where the outer diameter D ₁₃ of the small protrusion 13 for preventing the seal from coming off of the shaft 8 is relatively larger than the outer diameter ₁₂ of the shaft 8.

  In FIG. 6, the sealing protrusion 27 of the inner lip portion 1 is set to a position coincident with the tip surface of the inner lip portion 1 of the seal body 4. It is a structure that locks and also serves as a retainer.

FIG. 7 shows an embodiment of the present invention. In FIG. 7, the sealing protrusion (contact part) 28 of the inner lip 1 is formed into a surface with a small width in the axial direction, and the elastic biasing force of the opening end 25 of the spring 5 is the sealing protrusion. (Contact portion) 28 is easy to be transmitted to. That is, in FIG. 6, the axial center position of the opening end 25 of the spring 5 and the position of the seal projection 27 are slightly shifted. In FIG. 7, the planar seal projection (contact portion) is shown. At least a part of 28 is made to coincide with the axial direction position of the open end 25 of the spring 5, and the elastic urging force of the spring 5 is effectively utilized to increase the contact surface pressure with the shaft.

FIG. 8 shows the reference example of FIGS. 1 to 3 described above for comparison with FIGS. 4 to 7. The sealing protrusion 28 that contacts the surface of FIG. In addition to the triangular sealing projection 16 that is in contact with the projection, the sealing and locking projection 27 shown in FIG. 6 is additionally provided as a projection 17 on the distal end side.
4 to 8 correspond to the following examples , reference examples, and actual measurement results of the leak test.

Reference examples 1, 2, 3 , and 4 correspond to FIGS. 4, 5, 6, and 8 , respectively, and the radial dimension (thickness dimension) W of the seal S in the free state before the spring 5 is mounted is all. and 1.7 mm, all axial dimension H is 2.7 mm, 1.0 mm and thickness dimension T of the bottom wall portion 19, the inner diameter d ₁ of the bottom wall portion 19, the outer diameter d ₂ respectively 3.1 mm, and 5.9 mm, the seal body The above-mentioned modified PTFE was used as the material 4 and Inconel (registered trademark) was used as the material of the spring 5.

On the other hand, the (basic) outer diameter D ₁₂ of the small-diameter portion 12 of the shaft 8 is all set to 3.0 mm, and the outer diameter D ₁₃ of the small protrusion 13 for retaining the seal is 3.8 mm (1.27 × D ₁₂ ) in FIG. 5 is 3.6 mm (1.20 × D ₁₂ ), and FIGS. 6 to 8 is 3.2 mm (1.07 × D ₁₂ ). The inner diameter of the housing hole 7 was all 6.0 mm.
Table 1 shows the results of measuring the leakage using 20 kgf / cm ² of nitrogen gas as the leakage test fluid.

The following can be seen from Table 1 above.
Ratio axis diameter D ₁₂ of the outer diameter D ₁₃ of the sealing stopper for a small ridges 13, rapidly leak amount Q increases it exceeds 125% (Example 1). The reason for this is that when the inner lip portion 1 of the seal body 4 is greatly expanded in diameter when mounted, the small protrusion 13 is passed over, so that the seal projection 26 is expanded in diameter even after mounting, and a sufficient contact surface with the shaft. This is probably because the pressure cannot be obtained.

Therefore, as shown in FIG. 5 ( Reference Example 2), it is understood that when the percentage of (D ₁₃ / D ₁₂ ) is 120%, the leakage amount is suddenly improved to about 1/10.
Furthermore, as shown in FIG. 6 ( Reference Example 3), the percentage of (D ₁₃ / D ₁₂ ) is reduced to 107%, the degree of diameter expansion (stretching) when the seal is mounted is kept low, and the sealing protrusion 27 is provided. When formed on the tip surface 18 (as in FIG. 6), it is reduced to 4.8 mL / min.

As shown in FIG. 7 (Example 1 ), the percentage of (D ₁₃ / D ₁₂ ) is kept as it is, the sealing projection 28 is brought into contact with the shaft 8 in a band shape (planar shape), and the elasticity of the spring 5 is increased. Leakage is reduced to 1.4 mL / min if it is easily transmitted to the contact area.
Next, as shown in FIG. 8 ( Reference Example 4 ), if the seal projection 16 is changed so as to come into line contact with the shaft 8, and the locking projection 17 is added to the tip, the leakage will occur. It can be seen that it is significantly reduced to 0.3 mL / min.

In addition, when a leakage test was performed even on a prototype in which the percentage of (D ₁₃ / D ₁₂ ) was less than 107%, the seal would come out (jump out) from the storage recess 9. In this way, the lower limit value ( D ₁₃ / D ₁₂ ) at which the seal does not come out of the storage recess 9 is 107%.

As described above, the seal S comprising the resin seal body 4 in which the opening groove portion 3 is formed in one axial direction by the inner lip portion 1 and the outer lip portion 2, and the spring 5 provided in the opening groove portion 3 is provided. In the sealing structure attached to the housing recess 9 formed between the housing hole 7 and the shaft 8, the material of the seal body 4 is modified PTFE, and the shaft 8 includes the housing recess 9. A stepped surface 10 that forms the bottom surface is formed, and a small convex strip 13 for retaining the seal is attached to the shaft 8 at a position separated from the stepped surface 10 by a dimension H ₀ that is larger than the axial dimension H of the seal S. The small protrusion 13 that is formed integrally with the outer peripheral surface 8a and further has a gently tapered surface 13a that gradually decreases in diameter at the tip end side of the shaft 8, and the stepped surface 10 side has an axis 15 The outer surface of the small convex strip 13 for retaining the seal is a substantially irregular triangle having a locking surface 13b substantially orthogonal to Law D _13, by the shaft 8 is set to 105% to 110% of the outer diameter D ₁₂ of the portions forming the inner peripheral surface of the housing recess 9, the structure is simple, the volume of the high-pressure hydrogen gas seal structure Therefore, it is compact, and it is not necessary to attach a retaining member to the end of the shaft 8 or the housing hole 7 with a screw or the like. And the mounting | wearing operation | work to the storage recess 9 of the seal | sticker S can also be performed easily and rapidly. Therefore, it can be said that the sealing structure is suitable for valves such as a regulator electromagnetic valve of a hydrogen gas fuel cell vehicle.

  Furthermore, when the seal S is mounted in the storage recess 9, the expansion of the seal body 4 (the inner lip portion 1) can be suppressed, and a fluid leakage can be suppressed in a very small amount in use. Moreover, it is possible to prevent the seal S from coming out of the housing recess 9 due to pressure fluctuation or relative movement of the shaft 8 and the hole 7 after mounting (in use). In particular, the small protrusion 13 for preventing the seal from coming off is integrally formed with the shaft 8 as a substantially unequal triangular shape having a gently tapered surface 13a. It becomes possible. Moreover, since the small ridge 13 has a locking surface 13b substantially orthogonal to the shaft center 15, the seal S once mounted does not come out (do not jump out) from the storage recess 9.

Further, as described above, the resin seal main body 4 in which the opening groove portion 3 is formed in one axial center direction by the inner lip portion 1, the outer lip portion 2 and the bottom wall portion 19, and the spring 5 provided in the opening groove portion 3. In the high-pressure hydrogen gas seal, the inner lip portion 1 can be engaged with the seal protrusion 16 and the seal protrusion preventing small protrusion 13 formed on the outer peripheral surface 8a of the shaft 8. The projection 16 for sealing, and the sealing projection 16 is a triangular mountain shape having an axial center orthogonal surface 21 and a sloped surface 22 that gradually increases in diameter toward the bottom wall portion 19 side. 17 is a triangular mountain shape having a tip surface 18 of the inner lip portion 1, an axially orthogonal surface formed in a continuous flat surface shape, and a gradient surface 20 that gradually increases in diameter toward the bottom wall portion 19 side. The portion where the inner lip portion 1 directly contacts the shaft 8 has a double structure of the sealing projection 16 and the locking projection 17 so that the sealing (sealing) performance is extremely high. Is expensive.
Further, the locking projection 17 can surely prevent the seal S from coming out. In addition, the contact surface pressure of the seal projection 16 to the shaft 8 can be sufficiently increased, and excellent sealing (sealing) performance can be exhibited.

Further, as described above, the resin seal main body 4 mounted on the shaft 8 in which the opening groove portion 3 is formed in one axial center direction by the inner lip portion 1 and the outer lip portion 2 and fitted in the opening groove portion 3. In the high-pressure hydrogen gas seal comprising the provided spring 5, the seal body 4 is made of modified PTFE, and the wall thickness T of the bottom wall portion 19 on the back side of the opening groove 3 of the seal body 4 Is set to 35% to 50% of the axial dimension H of the seal body 4, and the cross-sectional shape of the spring 5 is U-shaped so that the opening ends 25, 25 are oriented in one axial direction. Axial direction in which the opening end portions 25 and 25 of the spring 5 come into contact with the inner and outer lip portions 1 and 2 and are elastically pressed to elastically bias the opening groove portion 3 in the opening direction. The operating position is matched with the axial position of the top of the sealing protrusion 16 of the inner lip 1 and the sealing protrusion 23 of the outer lip 2. , The pressure of hydrogen gas as the sealed fluid, for example, be as high as 50 MPa, can be suppressed sufficiently low gas permeation through the bottom wall portion 19. Moreover, it is possible to prevent the seal body 4 from becoming unnecessarily large.
Further, the elastic urging force of the spring 5 is effectively transmitted to the sealing protrusions 16 and 23. As a result, the contact surface pressure with respect to the outer peripheral surface of the shaft 8 and the inner peripheral surface of the housing hole 7 is sufficiently increased, and the sealing performance is reliably exhibited.
In addition, the amount of leakage is further reduced as compared with PTFE containing filler. Moreover, for example, it can be applied to high-pressure hydrogen gas as high as 50 MPa, leakage is minimized, and the creep resistance is excellent.

It is a figure explaining the use structure of one form of the seal | sticker for high pressure gas which has a close relationship with this invention , a positional relationship, and a dimensional relationship. It is sectional drawing of a seal | sticker. It is explanatory sectional drawing of the location where a seal | sticker is mounted | worn. It is explanatory drawing which shows the other reference example . It is explanatory drawing which shows another reference example . It is explanatory drawing which shows the other reference example . It is explanatory drawing which shows one Embodiment of this invention . FIG. 4 is an explanatory diagram showing a reference example of FIGS. 1 to 3 for comparison with others. It is sectional explanatory drawing which shows a prior art example.

1 inner lip 2 outer lip 4 seal body 5 spring 6 housing (body)
7 hole 8 shaft 8a outer peripheral surface 9 storage recess
10 Stepped surface
13 Small convex strip for retaining seal
15 axis
17 Locking protrusion
18 Tip surface
19 Bottom wall
20 Inclined surface
21 Axis orthogonal plane
22 Inclined surface
23 Seal projection
25 Open end
28 Seal projection S Seal T Wall thickness D ₀ , D ₁₂ , D ₁₃ Outer diameter H ₀ , H ₁ Axial dimension

Claims (1)

A resin seal body (4) mounted on the shaft (8) having an opening groove (3) formed in one axial center direction by the inner lip portion (1) and the outer lip portion (2), and the opening In the high-pressure hydrogen gas seal comprising a spring (5) provided in the groove (3), the material of the seal body (4) is modified PTFE, and the opening groove of the seal body (4) The thickness (T) of the bottom wall part (19) on the back side of (3) is set to 35% to 50% of the axial direction dimension (H) of the seal body (4), and the inner lip part The sealing projection (28) of (1) is formed in a band shape so as to contact the shaft (8), and the cross-sectional shape of the spring (5) is U-shaped and opens in one direction of the axis. The opening (25) (25) of the spring (5) is provided in the opening groove (3) so that the end (25) (25) faces, and the inner and outer lip (1) (2) In An axially acting position that contacts and elastically presses and elastically biases the opening groove (3) in the opening direction, and at least a part of the sealing protrusion (28) of the inner lip (1) When high-pressure hydrogen gas seal, characterized in that the axial position of the top of the sealing projection (23) of the outer lip portion (2), were matched.

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