JP2022167540A - Seal structure and valve device - Google Patents

Abstract

To provide a seal structure and a valve device capable of suppressing the stay of high pressure fluid on a backup ring and also suppressing the deformation of the backup ring.SOLUTION: The seal structure includes a U seal ring, and the backup ring provided on the low pressure part side of the U seal ring. On the outer peripheral face of the backup ring, a plurality of groove parts ranging from one end face of the backup ring to the other end face in the axial direction and recessed from the outer peripheral face toward the radial inside of the backup ring are formed at equal spaces in the peripheral direction of the backup ring, while a relationship of d≤1/5t is satisfied, where t is the thickness in the radial direction of the backup ring, and d is the depth of the groove part toward the radial inside.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to seal structures and valve devices.

Conventionally, as described in the valve device of Patent Document 1, for example, as a seal structure provided between a sleeve and a housing hole of the sleeve to seal the boundary between a high pressure portion and a low pressure portion, in addition to a U seal ring , with backup rings are known. The backup ring prevents the U-seal ring from being crushed and deformed by high pressure, and is provided on the low-pressure side with respect to the U-seal ring.

Japanese Patent Application Laid-Open No. 2016-80001

However, when the pressure in the high-pressure portion is rapidly reduced, the diameter of the U seal ring is reduced, which causes the pressure to be released to the low-pressure portion, and the high-pressure fluid may accumulate around the backup ring due to this pressure release. There is In this case, there is a risk that the backup ring will be deformed by the high pressure of the high-pressure fluid. Furthermore, when the high-pressure fluid accumulates and the magnitude relationship between the high-pressure part and the low-pressure part is reversed, the pressure difference causes the U-seal ring to deform due to pressure from the opposite direction. There was fear.

The present disclosure can be implemented as the following forms.

(1) According to one aspect of the present disclosure, a seal structure is provided. This seal structure is provided in a gap between an inner peripheral portion of an accommodation hole formed in a holding member and an outer peripheral portion of a shaft member accommodated in the accommodation hole, and prevents fluid from leaking in the gap. wherein, in the gap, one side in the axial direction of the shaft member across the seal structure is a high-pressure portion, and the other side in the axial direction is a low-pressure portion; a backup ring provided on the low-pressure portion side, wherein the outer peripheral surface of the backup ring has a plurality of grooves extending from one end face to the other end face of the backup ring in the axial direction, the outer peripheral surface A plurality of grooves that are recessed radially inward of the backup ring are formed at equal intervals in the circumferential direction of the backup ring, and the thickness of the backup ring in the radial direction is t, Assuming that the depth inward in the radial direction is d, the relationship d≦1/5t is satisfied.
Here, "equally spaced in the circumferential direction" is not limited to "equally spaced" at the same exact angle, but in light of the common technical knowledge in the relevant technical field, the range that is usually judged to be "equally spaced" If it has the same identity as According to this aspect, in a normal pressure holding state, the U seal ring receives pressure from the high pressure section and expands to maintain airtightness. On the other hand, when the pressure in the high-pressure part is suddenly decompressed temporarily, the shape of the U seal ring returns and shrinks, and even if a small amount of fluid (high-pressure fluid) in the high-pressure part leaks to the backup ring side, It escapes to the low pressure side through the groove formed in the backup ring. Therefore, it is possible to prevent the high-pressure fluid from accumulating around the backup ring, and to prevent deformation of the backup ring.
In addition, since the grooves are formed at regular intervals in the circumferential direction, the surface pressure acting on the backup ring can be made uniform, and the pressure can be applied in a well-balanced manner compared to the case where the grooves are concentrated in one place. can escape. Furthermore, if the depth of the groove in the radial direction is too large, there is concern that shearing may occur from the radially inner tip, or the supporting force as a backup of the U seal ring may become weak. In this case, deformation of the U seal ring causes leakage of the high-pressure fluid. In that respect, the groove portion of the above-described form satisfies the relationship d ≤ 1/5t in the relationship between the radial thickness t and the depth d. This makes it possible to avoid the possibility of the occurrence of .
(2) In the above aspect, the groove portion may have a shape in which the width in the circumferential direction becomes smaller toward the inner side in the radial direction from the outer peripheral surface. According to this aspect, when the groove is formed by cutting from the outer peripheral surface, the shape of the groove becomes smaller toward the inner side in the radial direction from the outer peripheral surface, so the shape of the groove becomes larger toward the inner side in the radial direction. The manufacturing work is easy compared to the conventional shape.
(3) In the above embodiment, a condition of 0°<θ≦60° may be satisfied, where θ is the central angle corresponding to the width of the groove in the circumferential direction. If the center angle θ corresponding to the width of the groove in the circumferential direction is too large, the function of preventing deformation on the outer peripheral surface of the backup ring may deteriorate. , can retain the anti-deformation function.
(4) In the above aspect, the fluid may be hydrogen gas or helium gas. According to this form, it is possible to obtain a seal structure suitable for equipment handling hydrogen gas or helium gas at an ultrahigh pressure exceeding 70 MPa, for example.
(5) In the above aspect, the shaft member is relatively movable with respect to the holding member,
The U seal ring and the backup ring may be provided in a circumferentially continuous mounting groove formed in either one of the inner peripheral portion of the housing hole and the outer peripheral portion of the shaft member. . According to this aspect, deformation of the backup ring and the U-seal ring can be suppressed at the sliding portion between the shaft member and the housing hole of the holding member, where seal leakage is likely to occur.
(6) According to another aspect of the present disclosure, a valve device is provided. The valve device is a valve device that opens and closes a gas flow path, and includes the seal structure of the above-described form, the holding member, and the shaft member, and the gas flow path is opened by moving relative to the holding member. and the shaft member functioning as a valve stem that opens and closes the .

1 is a cross-sectional view that schematically shows a schematic configuration of a valve device that includes a seal structure according to a first embodiment of the present disclosure; FIG. FIG. 4 is a plan view showing a backup ring; It is a figure in order to demonstrate the pressure which acts on seal structure. It is a figure in order to demonstrate the pressure which acts on seal structure. FIG. 4 is a diagram showing the change in pressure applied to the seal structure over time; It is a figure explaining the state of the backup ring after a test. It is a figure explaining the state of the backup ring after a test by a comparative form. FIG. 11 is a plan view showing a backup ring in another embodiment; FIG. 11 is a plan view showing a backup ring in another embodiment;

A. Embodiment:
A1. Overall configuration of the valve device 100:
FIG. 1 is a cross-sectional view that schematically shows a schematic configuration of a valve device 100 that includes a seal structure 40 according to the first embodiment of the present disclosure. The valve device 100 of the first embodiment is, for example, a shutoff valve for opening and closing a flow path for supplying hydrogen gas in a hydrogen dispenser arranged in a hydrogen station. A hydrogen dispenser is a device that directly fills a fuel cell vehicle (FCV) with high-pressure (eg, 70 MPa to 90 MPa) hydrogen gas. The configuration of the valve device 100 will be described below.

As shown in FIG. 1, the valve device 100 includes a valve body 10, a stem 20, a gland 30, and a seal structure 40. The valve body 10 has a cylindrical shape with an upper base 11 and accommodates a gland 30, a stem 20 and a seal structure 40 therein. Hereinafter, the upper side in FIG. 1 will be referred to as "upper" and the lower side as "lower". The vertical direction in FIG. 1 coincides with the axial direction of the stem 20 (the direction in which the central axis C of the stem 20 extends). 1 is the "one side" of the axial direction, and the upper side of FIG. 1 is the "other side" of the axial direction.

In FIG. 1, a high-pressure gas flow path (not shown) is provided below the stem 20 . In FIG. 1, above the stem 20, a driving section (not shown) for driving the stem 20 is provided. The stem 20 has a small diameter portion 21 and a large diameter portion 22 . The large diameter portion 22 is coaxial with the small diameter portion 21 and positioned below the small diameter portion 21 . The upper end of the small diameter portion 21 is connected to the driving portion. A lower end of the large diameter portion 22 is connected to a valve body (not shown).

The valve body is, for example, a needle valve, and by mechanically moving the stem 20 and the valve body up and down by a drive unit, the high-pressure gas flow path can be opened and closed. Further, the valve device 100 may be configured such that the valve body is a ball valve, and the high-pressure gas flow path is opened and closed by electromagnetically rotating the stem 20 and the valve body around the central axis C by a driving portion composed of a solenoid portion. . The stem 20 corresponds to a "shaft member" and is a "valve stem" capable of relative movement with respect to the gland.

The gland 30 is a cylindrical member through which a housing hole 31 for housing the stem 20 is formed, and is fixed inside the valve body 10 . The gland 30 is a pedestal that suppresses the wobble of the stem 20, and has the function of holding the stem 20 so that the central axis C is maintained vertical. The ground 30 corresponds to a "holding member". In the gland 30, an outer peripheral groove 32 continuous in the circumferential direction is formed on the outer peripheral surface near the center in the axial direction. Two similar seal rings (O-rings) 33 and 34 are mounted in the outer peripheral groove 32 so as to be aligned in the axial direction.

In the gland 30, an inner peripheral groove 35 continuous in the circumferential direction is formed on the inner peripheral surface near the center in the axial direction. The inner peripheral groove 35 is provided slightly above the outer peripheral groove 32 in the axial direction. A U-seal ring 41 and a backup ring 42 are mounted in the inner peripheral groove 35 so as to be aligned in the axial direction. The inner circumferential groove 35 corresponds to a "mounting groove". The backup ring 42 is provided on the other side of the U seal ring 41 in the axial direction (on the upper side in FIG. 1 and on the side of the low pressure portion Lp, which will be described later). Moreover, in the attached state, the outer diameters of the U seal ring 41 and the backup ring 42 are substantially the same.

A seal structure 40 is composed of the U seal ring 41 and the backup ring 42 . That is, the seal structure 40 is provided in the gap (including the inner peripheral groove 35) between the inner peripheral portion 36 of the housing hole 31 and the outer peripheral portion 23 of the stem 20 (small diameter portion 21), and prevent leakage of hydrogen gas from one to the other.

The U seal ring 41 is made of a fluororesin material such as PTFE. The U seal ring 41 includes a U ring 43 having a U-shaped cross section on a plane including the central axis C, a coil-shaped metal spring 44 fitted in the U-shaped recess and having excellent bending fatigue resistance, This is a composite seal that combines The backup ring 42 is made of a fluororesin material such as PTFE that is harder than the U seal ring 41 . The backup ring 42 is a seal ring member having a rectangular cross section on a plane including the central axis C. As shown in FIG.

In FIG. 1, the line where the U seal ring 41 is installed in the axial direction and where the U seal ring 41 and the ground 30 are in contact forms a boundary L between the high pressure portion Hp and the low pressure portion Lp. In FIG. 1, the upper side of the boundary L is the low pressure section Lp, and the lower side is the high pressure section Hp. That is, one axial side of the seal structure 40 is the high pressure portion Hp, and the other axial side is the low pressure portion Lp.

The outer peripheral portion 23 of the stem 20 is not formed with a channel for intentionally circulating the high-pressure gas to the low-pressure portion Lp side. However, the gap between the outer peripheral portion of the large-diameter portion 22 and the inner peripheral portion of the valve body 10, the gap between the lower surface of the gland 30 and the upper surface of the large-diameter portion 22, and the gap between the outer peripheral portion 23 of the small-diameter portion 21 and the accommodation hole 31 The high-pressure gas flows through the gap with the inner peripheral portion 36 so as to leak out. In FIG. 1, the route R through which the high-pressure gas leaks from the high-pressure gas passage through each gap is indicated by a thick line. The seal structure 40 of the present disclosure prevents leakage of high pressure gas through this route R to the outside. Since the gap 12 between the upper bottom portion 11 of the valve body 10 and the outer peripheral portion 23 of the stem 20 is not sealed, the low pressure portion Lp above the boundary L is at atmospheric pressure.

A2. Detailed configuration of the backup ring 42:
FIG. 2 is a plan view showing the backup ring 42. FIG. FIG. 2 shows the backup ring 42 viewed from the axial direction. As shown in FIG. 2, a plurality of grooves 46 extending in the axial direction are formed on the outer peripheral surface 45 of the backup ring 42 at equal intervals in the circumferential direction. The groove portion 46 is formed continuously from one end face to the other end face in the axial direction, and is formed by notching radially inward of the backup ring 42 from the outer peripheral face 45 . Four grooves 46 in this embodiment are formed at regular intervals of 90 degrees in the circumferential direction.

Each groove 46 has a notch width in the circumferential direction that decreases radially inward from the outer peripheral surface 45, and has a substantially isosceles trapezoidal shape in plan view. Also, the central angle θ corresponding to the notch width in the circumferential direction of each groove portion 46 is about 20° to 30°. If the center angle θ is too large, the function of preventing deformation of the outer peripheral surface 45 of the backup ring 42 may deteriorate. Note that the corners of the groove portion 46 may be rounded as appropriate.

Further, the radial thickness t of the backup ring 42 and the notch depth d of each groove 46 toward the radial inside satisfy the relation of d≦1/5t. In this embodiment, the relationship is approximately d=1/5t. If the value of the notch depth d is too large, shearing around the groove 46 may occur or the sealing force may be insufficient. A detailed effect will be described later.

A3. Action of the groove 46 of the backup ring 42:
Next, the sealing function of the sealing structure 40 will be described. FIG. 3 is a diagram for explaining the pressure acting on the seal structure 40, and shows a pressure holding state. FIG. 4 is a diagram for explaining the pressure acting on the seal structure 40, and shows the state during rapid pressure reduction. As shown in FIG. 3, in a normal pressure holding state, the U-seal ring 41 is deformed by the stress due to the high-temperature and high-pressure gas acting in the direction from the high-pressure portion Hp to the low-pressure portion Lp as indicated by the arrow A1 and thermal expansion. It is open in the direction indicated by A2, and airtightness is maintained at the boundary L between the high pressure section Hp and the low pressure section Lp.

As shown in FIG. 3, the seal structure 40 normally maintains airtightness. The shape returns and the diameter is reduced, and high-pressure gas slightly leaks to the low-pressure portion Lp side.

At this time, the leaked high-pressure gas passes through the groove 46 of the backup ring 42 as indicated by an arrow A4, and furthermore, flows into the outer peripheral portion 23 of the stem 20 and the inner peripheral portion 36 of the gland 30 on the low-pressure portion Lp side of the backup ring 42. , and escapes to the atmosphere side from the gap 12 (see FIG. 1) between the upper bottom portion 11 and the outer peripheral portion 23 . Therefore, the high pressure gas does not stay around S of the backup ring 42 .

[effect]
(1) As described above, even if a small amount of high-pressure gas leaks inside the seal structure 40, in the first embodiment, the groove 46 is provided in the backup ring 42 so that the high-pressure gas does not accumulate. , the pressure can be released from the groove 46 to the atmosphere side. Therefore, the backup ring 42 can be prevented from being damaged by the high-pressure gas pool, and the high-pressure gas pool generates a counter pressure in the direction opposite to the original pressure holding state, as indicated by the arrow A5 in FIG. Damage to the U seal ring 41 due to this can also be prevented. This is because the U-seal ring 41 is a one-way seal and is crushed when a reverse pressure is applied.

Next, a durability test conducted by the present applicant using the seal structure 40 of the first embodiment will be considered. In the endurance test according to the present application, rapid pressurization and rapid depressurization of the seal structure 40 were repeated 30,000 times, and then the state of the U seal ring 41 was observed. FIG. 5 shows the change in pressure applied to the seal structure 40 over time. As shown in FIG. 5, rapid pressure reduction from 90 MPa to 0 MPa was performed once every 10 seconds.

FIG. 6 is a diagram for explaining the state of the U-seal ring 41 after the rapid pressure reduction shown in FIG. . As shown in FIG. 6, in the U seal ring 41 of the first embodiment, deformation of the metal spring 44 and the U ring 43 was not observed, which was good. Also, no leakage of high pressure gas was measured.

FIG. 7 is a diagram for explaining the state of the U seal ring 51 in the comparative embodiment after 30,000 rapid pressure reductions similar to those in FIG. 5 are performed. It is shown. The U seal ring 51 of the comparative example is arranged together with a conventional backup ring in which the groove portion 46 satisfying the relationship of d≦1/5t is not formed. As shown in FIG. 7, it was confirmed that in the U seal ring 51 of the comparative example, the metal spring 54 was partially crushed and damaged. Moreover, the leakage amount of the high-pressure gas obtained by measurement was 7500 ppm. From the above, it was confirmed that, in the seal structure 40 of the first embodiment, leakage of high-pressure gas can be suppressed and the durability is improved as compared with the comparative form.

(2) Since the grooves 46 in the first embodiment are formed at regular intervals in the circumferential direction, the surface pressure acting on the backup ring 42 can be made uniform, and the grooves 46 are concentrated at one location. The pressure can be released in a well-balanced manner compared to the case where the Furthermore, if the notch depth d in the radial direction of the groove portion 46 is too large, shearing may occur from the radially inner tip, which is the notch destination, or the supporting force as a backup of the U seal ring 41 may become weak. is concerned. In this case, deformation of the U seal ring 41 causes leakage of the high-pressure fluid. In this respect, the groove portion 46 of the first embodiment satisfies the relationship d≦1/5t in the relationship between the radial thickness t and the depth d. Therefore, it is possible to avoid the risk of occurrence of shearing and lack of backup force, and it is possible to suppress the retention of the high-pressure fluid.

(3) The notch width in the circumferential direction of the groove portion 46 in the first embodiment is shaped such that the width of the notch in the circumferential direction becomes smaller toward the inner side in the radial direction from the outer peripheral surface 45 . Therefore, when the groove 46 is formed by cutting from the outer peripheral surface 45, the manufacturing work is easier than when the shape of the groove 46 becomes larger toward the inner side in the radial direction.

(4) In the first embodiment, the center angle θ corresponding to the notch width in the circumferential direction of the groove portion 46 is approximately 20 to 30°, within the range of 0°<θ≦60°. If the central angle θ corresponding to the notch width in the circumferential direction of the groove portion 46 is too large, the function of preventing deformation of the outer peripheral surface 45 of the backup ring 42 may deteriorate. The function can be preferably retained.

B. Other embodiments:
(B1) FIG. 8 is a plan view showing a backup ring 61 in another embodiment. Although the groove 46 of the first embodiment has an isosceles trapezoidal shape in plan view, it may be formed as a recess gently curved inward in the radial direction like the groove 62 shown in FIG. . The grooves are equally spaced in the circumferential direction, and the relationship between the radial thickness t and the notch depth d satisfies the relationship d≦1/5t.

(B2) FIG. 9 is a plan view showing a backup ring 71 in another embodiment different from FIG. As another form of the groove portion 46, as shown in FIG. 9, eight groove portions 72 having a triangular shape in plan view may be formed at equal intervals in the circumferential direction. In addition, the number of grooves 46 can be changed variously, such as two, three, or five.

(B3) In addition, the notch width in the circumferential direction of the groove portion 46 becomes smaller as it goes radially inward from the outer peripheral surface 45. good.

(B4) The groove portion 46 was formed to extend in the axial direction, but it may be formed continuously from one end surface to the other end surface in the axial direction, and may extend obliquely with respect to the circumferential direction. .

(B5) In the valve device 100 and the seal structure 40 of the first embodiment, hydrogen gas is used as the sealing fluid, but helium gas may also be used.

(B6) Although the valve device 100 having the seal structure 40 of the first embodiment is a shutoff valve, it may be a switching valve that switches between a plurality of flow paths.

(B7) The backup ring 42 of the first embodiment has a rectangular cross section along the plane passing through the central axis C, but may have a circular or other shape.

(B8) The seal structure 40 of the first embodiment is applied to the inside of the valve device 100, but application of the seal structure 40 of the present disclosure is not limited to the valve device 100. For example, it may simply be provided at the outer wall portion of the fluid flow path where high pressure acts to prevent leakage.

The present disclosure is not limited to the above embodiments, and can be implemented in various configurations without departing from the scope of the present disclosure. For example, the technical features in each embodiment corresponding to the technical features in each form described in the outline of the invention are used to solve some or all of the above problems, or In order to achieve some or all of them, it is possible to appropriately replace or combine them. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10... Valve body 11... Upper base part 12... Gap 20... Stem 21... Small diameter part 22... Large diameter part 23... Periphery part 30... Gland 31... Accommodating hole 32... Peripheral groove 35... Inner peripheral groove 36 Inner peripheral portion 40 Seal structure 41 U seal ring 42 Backup ring 43 U ring 44 Metal spring 45 Outer peripheral surface 46 Groove 100 Valve device .

Claims (6)

A seal structure provided in a gap between an inner peripheral portion of an accommodation hole formed in a holding member and an outer peripheral portion of a shaft member accommodated in the accommodation hole to prevent leakage of fluid in the gap,
In the gap, one side in the axial direction of the shaft member across the seal structure is a high pressure portion, and the other side in the axial direction is a low pressure portion,
a U seal ring;
a backup ring provided closer to the low pressure section than the U seal ring;
with
The outer peripheral surface of the backup ring has a plurality of grooves extending from one end face to the other end face of the backup ring in the axial direction, the grooves being recessed radially inward of the backup ring from the outer peripheral face. A plurality of grooves are formed at regular intervals in the circumferential direction of the backup ring,
A seal structure satisfying a relationship of d≦1/5t, where t is the radial thickness of the backup ring and d is the radially inward depth of the groove. 2. The seal structure according to claim 1, wherein the groove portion has a shape in which the width in the circumferential direction decreases toward the inner side in the radial direction from the outer peripheral surface. 3. The seal structure according to claim 1, wherein a condition of 0°<θ≦60° is satisfied, where θ is a central angle corresponding to the width of the groove in the circumferential direction. The seal structure according to any one of claims 1 to 3, wherein the fluid is hydrogen gas or helium gas. The shaft member is movable relative to the holding member,
3. The U-seal ring and the backup ring are provided in a circumferentially continuous mounting groove formed in one of the inner peripheral portion of the housing hole and the outer peripheral portion of the shaft member. The seal structure according to any one of claims 1 to 4. A valve device for opening and closing a gas flow path,
a seal structure according to any one of claims 1 to 5;
the holding member;
the shaft member functioning as a valve stem that opens and closes the gas flow path by moving relative to the holding member;
valve device.

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