Composite seal material for compressors

Abstract

To provide a composite seal material for a compressor enabling space saving and elongation of a service life.SOLUTION: A composite seal material 1 for a compressor includes: a first annular seal group 1a fitted to an annular groove of a piston 10; and a second annular seal group 1b. The first annular seal group 1a includes: a first annular sliding member 16; a first annular inner support member 18 supporting the first annular sliding member 16 from the inner side in the radial direction of the first annular sliding member 16; a first annular side face support member 15 supporting the first annular sliding member 16 and the first annular inner support member 18 from the low pressure side; and a first annular support member 14 supporting the first annular inner support member 18 from the inner side in the radial direction of the first annular inner support member 18, supporting the first annular side face support member 15 from the inner side in the radial direction of the first annular side face support member 15 and supporting the first annular side face support member 15 from the low pressure side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a composite seal for a compressor. [Background technology]

[0002] BACKGROUND ART Conventionally, a technique for ensuring airtightness by using a group of piston rings provided on the outer peripheral surface of a piston used in a reciprocating compressor that compresses gas to high pressure is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5435245 Summary of the Invention [Problem to be solved by the invention]

[0004] Hydrogen gas and other gases used in hydrogen stations need to be compressed to high pressures. Therefore, high sealing performance is required for compressing hydrogen gas and other gases. Here, in a piston ring group used in the reciprocating compressor described in Patent Document 1, multiple stages are required to improve sealing performance, which requires a long axial space. Furthermore, in a piston ring group used in the reciprocating compressor described in Patent Document 1, wear of the piston rings directly affects sealing performance, resulting in a shorter lifespan.

[0005] An object of the present disclosure is to provide a composite sealing material for a compressor that enables space saving and a long life. [Means for solving the problem]

[0006] The composite seal for a compressor of the present disclosure is attached to an annular groove of a piston disposed at the tip of a piston rod used in a reciprocating compressor, and divides the inside of the cylinder into a high-pressure side and a low-pressure side. The composite seal for a compressor includes a first group of annular seals attached to the annular groove of the piston, and a second group of annular seals attached to the annular groove on the low-pressure side of the first group of annular seals along the axial direction of the piston rod. The first annular seal group includes a first annular sliding member, a first annular inner support member that supports the first annular sliding member from the radially inner side of the first annular sliding member, a first annular side support member that supports the first annular sliding member and the first annular inner support member from the low-pressure side, and a first annular support member that supports the first annular inner support member from the radially inner side of the first annular inner support member, supports the first annular side support member from the radially inner side of the first annular side support member, and supports the first annular side support member from the low-pressure side.

[0007] The second annular seal group includes a second annular sliding member, a second annular inner support member that supports the second annular sliding member from the radially inner side of the second annular sliding member, a second annular side support member that supports the second annular sliding member and the second annular inner support member from the low-pressure side, and a second annular support member that supports the second annular side support member from the low-pressure side.

[0008] The first annular side support member has a lower rigidity than the first annular support member, and the second annular side support member has a lower rigidity than the second annular support member.

[0009] The radial collapse rate of the first annular inner support member is less than the radial collapse rate of the second annular inner support member.

[0010] The annular groove has a first groove portion provided at a first depth in the radial direction and a second groove portion located on the low-pressure side of the first groove portion and shallower than the first depth. The first annular seal group is fitted into the first groove portion, and the second annular seal group is fitted into the second groove portion.

[0011] The composite seal for a compressor further includes a third annular seal group between the first annular seal group and the second annular seal group along the axial direction of the piston rod. The third annular seal group includes a third annular sliding member, a third annular inner support member that supports the third annular sliding member from the radially inner side of the third annular sliding member, a third annular side support member that supports the third annular sliding member and the third annular inner support member from the low-pressure side, and a third annular support member that supports the third annular inner support member from the radially inner side of the third annular inner support member, supports the third annular side support member from the radially inner side of the third annular side support member, and supports the third annular side support member from the low-pressure side. The third annular seal group is fitted into the first groove. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a composite sealing material for a compressor that enables space saving and a long life. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a piping diagram of a two-stage reciprocating compressor according to a first embodiment. [Figure 2] 1 is a diagram showing a composite sealing material for a compressor according to a first embodiment attached to a piston. FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view of the III-III portion of FIG. 2. [Figure 4] 1 is a perspective view of a composite sealing material for a compressor according to a first embodiment. [Figure 5] 10 is a diagram showing a composite sealing material for a compressor according to a second embodiment attached to a piston. FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view of the portion VI-VI in FIG. 5. [Figure 7] FIG. 10 is a perspective view of a composite sealing material for a compressor according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] The mounting structure of the adsorption / detachment member according to each embodiment of the present disclosure will be described below with reference to the drawings. In the embodiments described below, when reference is made to the number, quantity, etc., the scope of the present disclosure is not necessarily limited to that number, quantity, etc., unless otherwise specified. The same reference numerals are used for the same or equivalent parts, and redundant descriptions may not be repeated. It is intended from the outset that the configurations in the embodiments may be used in appropriate combinations.

[0015] [Embodiment 1] FIG. 1 is a piping diagram of a two-stage reciprocating compressor according to a first embodiment. As shown in FIG. 1, a reciprocating compressor 100 according to this embodiment includes a low-stage compression section 110 and a high-stage compression section 120. The compression sections 110 and 120 are driven by the same or different drive sections 130.

[0016] Low-stage compression section 110 includes a cylinder 112 having a compression chamber 111, and a piston 113 arranged so as to be able to slide back and forth within cylinder 112. Low-stage compression section 110 draws gas into compression chamber 111 of cylinder 112 by the reciprocating sliding of piston 113, and compresses it to a predetermined pressure. The gas compressed in low-stage compression section 110 is stored in tank 115 through communication passage 114, and is maintained at a predetermined pressure (for example, 35 MPa).

[0017] High-stage compression section 120 includes cylinder 122 having compression chamber 121 that is connected to tank 115 via communication passage 116, and piston 10 and piston 123 that are arranged so as to be able to slide back and forth within cylinder 122. Piston 10 is provided at the tip of piston rod 51. Piston 123 is provided at the tip of piston rod 131. Piston rod 51 and piston rod 131 are connected via piston 123.

[0018] The high-stage compression section 120 is configured to suck the compressed gas discharged from the low-stage compression section 110 and stored in a tank 115 into a compression chamber 121 of a cylinder 122 by the reciprocating sliding of a piston 10, and compress it to a one-stage higher pressure (for example, 100 MPa). The compressed gas compressed in the high-pressure compression section 120 is delivered through a delivery passage 124. A cooler 125 for cooling the compressed gas compressed in the compression section 120 is provided in the delivery passage 124.

[0019] Compressed gas at a predetermined pressure (e.g., 30 MPa) lower than the compressed gas drawn into compression chamber 121 is introduced into the gap between piston 10 and piston 123 through gas introduction passage 156. This makes it possible to uniformly adjust the pressing force against the inner surface of cylinder 122.

[0020] The drive unit 130 includes a piston rod 131 having one end connected to the base end of the piston 123, a crosshead 133 to which the other end of the piston rod 131 is connected and which is arranged so as to be able to slide back and forth within a guide cylinder 132, a connecting rod 134 having one end connected to the crosshead 133, a crankshaft 136 to which the other end of the connecting rod 134 is connected and which is rotatably supported by a crankcase 135, and a drive motor 138 connected to the crankshaft 136 so as to be able to transmit power through a power transmission mechanism 137 consisting of a pulley and a belt. The drive unit 130 uses the rotational force of the drive motor 138 to rotate the crankshaft 136 and cause the crosshead 133 to slide back and forth within the guide cylinder 132, ultimately causing the piston 10 and piston 123 to slide back and forth within the cylinder 122.

[0021] A cylinder 122 is attached within crankcase 135 via a distance piece (not shown). Compressed gas that leaks from cylinder 122 into the distance piece is returned from a return port provided in the distance piece through a return passage 147 to the suction side of compression section 110 on the lower stage side. A filter 148 is arranged in return passage 147.

[0022] The following describes the detailed structure of the composite sealing material 1 for a compressor attached to the tip 54 of the piston 10. Fig. 2 is a diagram showing the composite sealing material 1 for a compressor according to the first embodiment attached to the piston 10, Fig. 3 is an enlarged cross-sectional view of part III-III in Fig. 2, and Fig. 4 is a perspective view of the composite sealing material 1 for a compressor according to the first embodiment.

[0023] As shown in Fig. 2, the direction along the axis of piston rod 51 is called the axial direction, and the direction from the axis of piston rod 51 toward the outer surface of composite sealing material 1 for a compressor is called the radial direction. As shown in Fig. 2, the side of tip end 54 of piston rod 51 where compression chamber 111 is located is called the high-pressure side, and the side opposite the high-pressure side is called the low-pressure side. Composite sealing material 1 for a compressor divides the inside of cylinder 122 into a high-pressure side and a low-pressure side.

[0024] 2 to 4, the piston 10 includes the composite seal material for a compressor 1 disposed on the tip 54 of the piston rod 51, a washer 52, and a nut 53. The composite seal material for a compressor 1 is fixed to the tip 54 of the piston rod 51 by tightening the nut 53 with the washer 52 interposed therebetween.

[0025] The composite seal material 1 for a compressor is installed in an annular groove of a piston 10 disposed at the tip of a piston rod 51 used in a reciprocating compressor 100. The composite seal material 1 for a compressor includes a first annular seal group 1a installed in a first groove portion 51a provided at a first depth in the radial direction, and a second annular seal group 1b installed in a second groove portion 51b provided at a second depth in the radial direction that is shallower than the first depth. The second annular seal group 1b is located on the lower-pressure side of the first annular seal group 1a in the axial direction.

[0026] The first annular seal group 1a has a first annular sliding member 16, a first annular inner support member 18, a first annular side support member 15, and a first annular support member 14. The first annular sliding member 16 is a member that slides on the inner surface of the cylinder 112 when the piston 10 reciprocates. The first annular sliding member 16 is made of, for example, polytetrafluoroethylene (hereinafter referred to as PTFE).

[0027] The first annular inner support member 18 supports the first annular sliding member 16 from the radially inner side of the first annular sliding member 16. Inner support Component 1 8 The first cyclic member is made of, for example, fluororubber (hereinafter referred to as FKM). Inner support Component 1 8 is called an O-ring. The sealing material formed by combining the first annular sliding member 16 and the first annular inner support member 18 is called a slipper seal. Use of a slipper seal can reduce frictional resistance.

[0028] The first annular side support member 15 supports the first annular sliding member 16 and the first annular inner support member 18 from the low-pressure side. The first annular side support member 15 is made of, for example, polyether ether ketone (hereinafter referred to as PEEK). The first annular side support member 15 may also be made of other resins such as PTFE and POM (polyacetal).

[0029] The first annular support member 14 supports the first annular inner support member 18 from the radially inner side of the first annular inner support member 18, supports the first annular side support member 15 from the radially inner side of the first annular side support member 15, and supports the first annular side support member 15 from the low-pressure side. The first annular support member 14 is made of, for example, CAC603, which is a lead bronze casting. However, other materials may be used for the first annular support member 14 as long as they are metals with relatively low hardness, such as CAC603. The first annular support member 14 has an L-shaped cross section.

[0030] The outer circumferential surface of the first annular support member 14 has a long axial dimension, which allows the first annular support member 14 to function as a bearing. This eliminates the need to install a separate wear ring to serve as a bearing.

[0031] The first annular support member 14 supports, from the low-pressure side, a resin first annular side support member 15 made of metal, which supports a first annular sliding member 16, which is a slipper seal, and a first annular inner support member 18. Here, the rigidity of the resin first annular side support member 15 is lower than the rigidity of the metal first annular support member 14. This increases the rigidity of the low-pressure side of the first annular seal group 1a, making it a mechanism with excellent pressure resistance.

[0032] The second annular seal group 1b is located on the lower pressure side than the first annular seal group 1a. The second annular seal group 1b has a second annular sliding member 13, a second annular inner support member 17, a second annular side support member 12, and a second annular support member 11. The second annular sliding member 13 is a member that slides on the inner surface of the cylinder 112 when the piston 10 reciprocates. The second annular sliding member 13 is made of, for example, PTFE.

[0033] The second annular inner support member 17 supports the second annular sliding member 13 from the radially inner side of the second annular sliding member 13. The second annular inner support member 17 is made of, for example, FKM. Inner support The member 17 is called an O-ring. The sealing material formed by combining the second annular sliding member 13 and the second annular inner support member 17 is called a slipper seal. The use of a slipper seal can reduce frictional resistance.

[0034] The second annular side support member 12 supports the second annular sliding member 13 and the second annular inner support member 17 from the low-pressure side. The second annular side support member 12 is made of, for example, PEEK. The second annular side support member 12 may also be made of other resins such as PTFE and POM.

[0035] The second annular support member 11 supports the second annular side support member 12 from the low-pressure side. The second annular support member 11 is made of, for example, CAC703, which is an aluminum bronze casting. The second annular support member 11 may be made of any other material as long as it is a metal with a relatively low hardness, such as CAC703. The second annular support member 11 has a rectangular cross section.

[0036] The second annular support member 11 supports, from the low-pressure side, a resin second annular side support member 12 made of metal, which supports the second annular sliding member 13, which is a slipper seal, and the second annular inner support member 17. Here, the rigidity of the resin second annular side support member 12 is lower than the rigidity of the metal second annular support member 11. This increases the rigidity of the low-pressure side of the second annular seal group 1b, making it a mechanism with excellent pressure resistance.

[0037] The annular groove provided in the piston rod 51 has a first groove portion 51a provided at a first depth in the radial direction and a second groove portion 51b on the lower-pressure side of the first groove portion 51a and shallower than the first depth. The first annular seal group 1a is fitted into the first groove portion 51a. The second annular seal group 1b is fitted into the second groove portion 51b. The annular groove of the piston rod 51 has a multi-stage structure that becomes shallower toward the tip portion 54, and therefore can be easily machined using a lathe or the like.

[0038] In the composite seal material 1 for a compressor, the first annular sliding member 16 and the first annular inner support member 18, both of which have a slipper seal structure, are arranged in the first groove portion 51a, and the second annular sliding member 13 and the second annular inner support member 17, both of which have a slipper seal structure, are arranged in the second groove portion 51b. By making the slipper seal mounting groove a divided groove in this way, the composite seal material 1 for a compressor can be easily assembled to the piston rod 51. The composite seal material 1 for a compressor has a multi-stage slipper seal structure, which can improve sealing performance.

[0039] The radial crushing ratio of the first annular inner support member 18 is set lower than the radial crushing ratio of the second annular inner support member 17. The crushing ratio is a value that indicates how much the O-ring is compressed relative to its wire diameter. Crushing ratio = crushing allowance ÷ O-ring wire diameter × 100. The crushing allowance indicates the distance that the O-ring is compressed while installed in the groove. For example, the radial crushing ratio of the first annular inner support member 18 is set to 0% to 3%, and the radial crushing ratio of the second annular inner support member 17 is set to 10% to 20%.

[0040] By lowering the sealing performance on the high-pressure side compared to the low-pressure side, it is possible to provide a pressure reduction effect to the high-pressure side slipper seal structure. By increasing the sealing performance on the low-pressure side compared to the high-pressure side, it is possible to improve the sealing performance of the low-pressure side slipper seal structure. As a result, even when compressing gases such as hydrogen gas, which require high pressure and high speed, the composite seal material 1 for compressors can reduce the pressure applied to the low-pressure side while maintaining its sealing performance, thereby extending the life of the composite seal material 1 for compressors.

[0041] The shape of the composite seal material 1 for a compressor takes into consideration the arrangement and materials of each component of the first annular seal group 1a and the second annular seal group 1b. As a result, the composite seal material 1 for a compressor can be a low-sliding seal under high pressure, while also saving space by shortening its axial length.

[0042] [Embodiment 2] The following describes the detailed structure of the composite sealing material 1A for a compressor attached to the tip of the piston 10A according to embodiment 2. Fig. 5 is a diagram showing the composite sealing material 1A for a compressor according to embodiment 2 attached to the piston 10A, Fig. 6 is an enlarged cross-sectional view of the portion VI-VI in Fig. 5, and Fig. 7 is a perspective view of the composite sealing material 1 for a compressor according to embodiment 2.

[0043] The composite seal material 1A for a compressor of the second embodiment differs from the composite seal material 1 for a compressor of the first embodiment in that a third annular seal group 1c is arranged between the first annular seal group 1a and the second annular seal group 1b along the axial direction of the piston rod 51. In the composite seal material 1A for a compressor of the second embodiment, the configurations of the first annular seal group 1a and the second annular seal group 1b are the same as those of the composite seal material 1 for a compressor of the first embodiment, and therefore description thereof will be omitted.

[0044] The third annular seal group 1c includes a third annular sliding member 26, a third annular inner support member 28, a third annular side support member 25, and a third annular support member 24. The third annular sliding member 26 is a member that slides on the inner surface of the cylinder 112 when the piston 10A reciprocates. The third annular sliding member 26 is made of, for example, PTFE.

[0045] The third annular inner support member 28 supports the third annular sliding member 26 from the radially inner side of the third annular sliding member 26. The third annular sliding member 26 is made of, for example, FKM. Inner support The member 28 is called an O-ring. The sealing material formed by combining the third annular sliding member 26 and the third annular inner support member 28 is called a slipper seal. Use of a slipper seal can reduce frictional resistance.

[0046] The third annular side support member 25 supports the third annular sliding member 26 and the third annular inner support member 28 from the low-pressure side. The third annular side support member 25 is made of, for example, PEEK. The third annular side support member 25 may also be made of other resins such as PTFE and POM.

[0047] The third annular support member 24 supports the third annular inner support member 28 from the radially inner side of the third annular inner support member 28, supports the third annular side support member 25 from the radially inner side of the third annular side support member 25, and supports the third annular side support member 25 from the low-pressure side. The third annular support member 24 is made of, for example, CAC603. Other materials may also be used for the third annular support member 24 as long as they are metals with relatively low hardness, such as CAC603. The third annular support member 24 has an L-shaped cross section.

[0048] The third annular support member 24 supports, from the low-pressure side, a resin third annular side support member 25 made of metal, which supports a third annular sliding member 26, which is a slipper seal, and a third annular inner support member 28. Here, the rigidity of the resin third annular side support member 25 is lower than the rigidity of the metal third annular support member 24. This increases the rigidity of the low-pressure side of the third annular seal group 1c, making it a mechanism with excellent pressure resistance.

[0049] The third annular seal group 1c is fitted into the first groove portion 51a, just like the first annular seal group 1a. The annular groove of the piston rod 51 has a multi-stage structure that becomes shallower toward the tip portion 54, making it easy to machine using a lathe or the like. Making the slipper seal mounting groove a divided groove makes it easier to assemble the composite seal material for a compressor 1A to the piston rod 51. The composite seal material for a compressor 1A has a multi-stage slipper seal structure, which allows for improved sealing performance.

[0050] The radial crushing ratio of the third annular inner support member 28 may be set to be between the radial crushing ratio of the first annular inner support member 18 and the radial crushing ratio of the second annular inner support member 17. This makes it possible to achieve both a longer life by providing a pressure reducing effect to the high-pressure side slipper seal structure and improved sealing performance from the high-pressure side to the low-pressure side.

[0051] [Other embodiments] In the above embodiment, the composite seal for a compressor may be formed using only the first annular seal group 1a. In the above embodiment, the composite seal for a compressor may be formed using four or more stages of annular seal groups.

[0052] In the above embodiment, the second annular support member 11 is made of CAC703, and the first annular support member 14 and the third annular support member 24 are made of CAC603. CAC703 is a material with higher rigidity than CAC603. The first annular support member 14, the second annular support member 11, and the third annular support member 24 may be made of the same material. Alternatively, the materials used for the first annular support member 14, the third annular support member 24, and the second annular support member 11, arranged from the high-pressure side to the low-pressure side, may have increasing rigidity.

[0053] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0054] 1, 1A Composite seal material for compressor, 1a First annular seal group, 1b Second annular seal group, 1c Third annular seal group, 10, 10A, 113, 123 Piston, 11 Second annular support member, 12 Second annular side support member, 13 Second annular sliding member, 14 First annular support member, 15 First annular side support member, 16 First annular sliding member, 17 Second annular inner support member, 18 First annular inner support member, 24 Third annular support member, 25 Third annular side support member, 26 Third annular sliding member, 28 Third annular inner support member, 51, 131 Piston rod, 51a First groove portion, 51b Second groove portion, 52 Washer, 53 Nut, 54 Tip portion, 100 Reciprocating compressor, 110, 120 Compression portion, 111, 121 Compression chamber, 112, 122 Cylinder Da .

Claims

1. A composite seal for a compressor is attached to an annular groove of a piston disposed at the tip of a piston rod used in a reciprocating compressor, and separates the inside of a cylinder into a high-pressure side and a low-pressure side, The composite sealing material for a compressor comprises: a first annular seal group mounted in the annular groove of the piston; a two-stage structure including a second annular seal group attached to the annular groove on the low-pressure side relative to the first annular seal group along the axial direction of the piston rod, The first annular seal group includes: a first annular sliding member; a first annular inner support member that supports the first annular sliding member from the radially inner side of the first annular sliding member; a first annular side support member that supports the first annular sliding member and the first annular inner support member from the low pressure side; a first annular support member that supports the first annular inner support member from the radially inner side of the first annular inner support member, supports the first annular side support member from the radially inner side of the first annular side support member, and supports the first annular side support member from the low-pressure side, The second annular seal group is a second annular sliding member; a second annular inner support member that supports the second annular sliding member from the radially inner side of the second annular sliding member; a second annular side support member that supports the second annular sliding member and the second annular inner support member from the low pressure side; a second annular support member that supports the second annular side support member from the low pressure side, A composite seal for a compressor, wherein the first annular inner support member has a radial crush rate that is lower than the radial crush rate of the second annular inner support member.

2. 2. The composite sealing material for a compressor according to claim 1, wherein the rigidity of the first annular side support member is lower than the rigidity of the first annular support member, and the rigidity of the second annular side support member is lower than the rigidity of the second annular support member.

3. the annular groove has a first groove portion provided at a first depth in a radial direction and a second groove portion located on the low-pressure side of the first groove portion and shallower than the first depth, the first annular seal group is fitted into the first groove portion, 3. The composite sealing material for a compressor according to claim 1, wherein the second annular seal group is fitted into the second groove portion.

4. A composite seal for a compressor is attached to an annular groove of a piston disposed at the tip of a piston rod used in a reciprocating compressor, and separates the inside of a cylinder into a high-pressure side and a low-pressure side, The composite sealing material for a compressor comprises: a first annular seal group mounted in the annular groove of the piston; a second annular seal group attached to the annular groove on the low-pressure side relative to the first annular seal group along the axial direction of the piston rod; a third annular seal group mounted in the annular groove between the first annular seal group and the second annular seal group along the axial direction of the piston rod, The first annular seal group includes: a first annular sliding member; a first annular inner support member that supports the first annular sliding member from the radially inner side of the first annular sliding member; a first annular side support member that supports the first annular sliding member and the first annular inner support member from the low pressure side; a first annular support member that supports the first annular inner support member from the radially inner side of the first annular inner support member, supports the first annular side support member from the radially inner side of the first annular side support member, and supports the first annular side support member from the low-pressure side, The second annular seal group is a second annular sliding member; a second annular inner support member that supports the second annular sliding member from the radially inner side of the second annular sliding member; a second annular side support member that supports the second annular sliding member and the second annular inner support member from the low pressure side; a second annular support member that supports the second annular side support member from the low pressure side, The third annular seal group is a third annular sliding member; a third annular inner support member that supports the third annular sliding member from the radially inner side of the third annular sliding member; a third annular side support member that supports the third annular sliding member and the third annular inner support member from the low pressure side; a third annular support member that supports the third annular inner support member from the radially inner side of the third annular inner support member, supports the third annular side support member from the radially inner side of the third annular side support member, and supports the third annular side support member from the low-pressure side, a radial crushing ratio of the first annular inner support member is lower than a radial crushing ratio of the second annular inner support member, and a radial crushing ratio of the third annular inner support member is set between the radial crushing ratios of the first annular inner support member and the second annular inner support member.

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