JP2006057834A - Seal construction of sliding part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the seal construction of the sliding part that can seal the interspace between a shaft and a cylinder appropriately. <P>SOLUTION: In the interspace between a shaft 11 and a cylinder 10 and the seal construction of the sliding part to seal by the first packing P1 and the second packing P2 that are arranged in series between the cylinder 10 and the shaft 11 inserted to the movement free in the cylinder 10, the first packing P1 established inside prepares the seal member 20 facing to the cylinder 10 inside and the backup ring 25 facing to the sliding part. The seal member 20 and the backup ring 25 are unified inseparably which attains to prevent the deterioration of the seal performance by preventing the isolation of the backup ring 25 from the seal member 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a seal structure for a sliding portion.

  Conventionally, the seal structure of this kind of sliding part is known as shown in FIG. 3, and the seal structure of this sliding part is, for example, a rod 2 that is a shaft of a hydraulic cylinder and a cylinder that is a cylinder. 3, the structure includes a first packing 4 and a second packing 5 arranged in series, and each packing 4, 5 is an annular groove provided on the inner peripheral side of the cylinder 3. It is inserted in 3a, 3b.

  Further, the first packing 4 located inside the cylinder 3 is composed of a U packing 6 as a sealing member and a backup ring 7 fitted in a notch provided on the inner peripheral side of the U packing 6. The second packing 5 located outside the cylinder 3 is constituted by a U packing.

  Then, the first packing 4 is brought into contact with the inner periphery of the annular groove 3a of the cylinder 3 and the outer periphery of the rod 2, and the second packing 5 is brought into contact with the inner periphery of the annular groove 3b of the cylinder 3 and the outer periphery of the rod 2. The rod 2 and the cylinder 3 are sealed to keep the cylinder 3 in an oil-tight state.

  Here, the first packing 4 is provided in order to prevent the high pressure in the cylinder 3 from acting directly on the second packing 5, so that the second packing 5 is only hydraulic oil that passes through the first packing 4. Will be sealed.

  That is, the first packing 4 functions as a so-called buffer seal that plays a role of reducing the pressure acting on the second packing 5.

Therefore, the seal structure of the sliding part as described above is used particularly when sealing equipment such as a hydraulic cylinder for construction equipment that is assumed to have a very high pressure inside the cylinder 3.
JP 2004-52854 A (from page 4, line 38 to page 4, line 42, FIG. 1)

  However, the above-described conventional sliding part seal structure may be pointed out to have the following adverse effects.

  That is, in the conventional configuration, the backup ring 7 is integrated by fitting in the notch of the U packing 6, but is not completely fixed to the U packing 6. If expansion and contraction is repeated for a long time, hydraulic oil enters and accumulates between the U packing 6 and the backup ring 7, and the backup ring 7 is released from the U packing 6.

  Here, the backup ring 7 is provided for the purpose of preventing the deformation of the inner lip of the U packing 6, but the space S between the first packing 4 and the second packing 5 due to the release of the backup ring 7. The hydraulic oil accumulates in the tank.

  That is, when hydraulic oil is accumulated between the U packing 6 and the backup ring 7, the U packing 6 is moved into the annular groove 3 a by the hydraulic oil accumulated between the U packing 6 and the backup ring 7 in FIG. 3. While being moved to the middle right and pressed against the right side wall of the annular groove 3a, the other backup ring 7 is moved to the left in FIG. When pressed against the left side wall of the groove 3 a, the hydraulic oil in the space S is prevented from returning into the cylinder 3.

  The accumulation of hydraulic oil in the space S is repeated every time the hydraulic cylinder 1 expands and contracts, and the hydraulic pressure in the space S gradually increases. Finally, the second oil pressure in the space S causes the second oil pressure. The packing 5 is strongly pressed against the rod 2 and melts and wears when the rod 2 moves, and there is a possibility that the gap between the rod 2 and the cylinder 3 cannot be properly sealed.

  Therefore, the present invention was devised in order to improve the above-described problems, and an object of the present invention is to provide a seal structure for a sliding portion capable of appropriately sealing between a shaft and a cylinder. Is to provide.

  In order to achieve the above object, the problem solving means in the present invention is a first packing and a second packing arranged in series between a cylinder and a shaft movably inserted into the cylinder. In the seal structure of the sliding portion that seals between the first packing, the first packing provided inside includes a seal member facing the inside of the cylinder and a backup ring facing the sliding portion, and the seal member and the backup ring Are integrated inseparably.

  According to the present invention, even if the relative movement of the shaft with respect to the cylinder is repeated for a long time, the seal member and the backup ring constituting the first packing are integrated so as not to be separated. Liquid such as hydraulic oil does not enter and accumulate in between.

  Therefore, since the backup ring is not separated from the seal member, the function of the sealing performance can be maintained, and the shaft and the tube can be appropriately sealed.

  That is, since liquid such as hydraulic oil does not enter and accumulate between the seal member and the backup ring, the liquid in the space between the first packing and the second packing returns to the inward side of the cylinder. Can be prevented.

  Therefore, liquid such as hydraulic oil that passes through the first packing is not accumulated in the space between the first packing and the second packing, and the pressure in the space does not increase abnormally, and the second packing is melted and worn. Therefore, the sealing performance of the second packing is not hindered.

  In addition, the seal structure of the sliding portion can prevent deterioration of the sealing performance of the first packing and the second packing, so that the cylinder is kept sealed even if the shaft is repeatedly moved for a long period of time. Can do.

  In addition, since the function of the first packing as a buffer seal is maintained without deterioration over a long period of time, the sealing performance of the second packing itself is also maintained over a long period of time, resulting in improved durability of both packings. Longer life can be achieved.

  Furthermore, since the pressure of the hydraulic oil acting on the second packing does not increase, the second packing is prevented from being pressed against the shaft or the cylinder with a force more than that required for sealing, and as a result, the shaft or the cylinder is prevented. Generation of excessive frictional force between the second packing and the second packing is prevented, and smooth movement of the shaft or cylinder is ensured.

  In the following description of the present embodiment, the present invention will be described as a case where the present invention is embodied in a hydraulic cylinder. FIG. 1 is an enlarged longitudinal sectional view of a seal portion of a hydraulic cylinder in which the sliding portion seal structure of the present invention is embodied. FIG. 2 is a schematic longitudinal sectional view of the hydraulic cylinder.

  As shown in FIG. 1, the seal structure of the sliding portion in the present embodiment is embodied in a hydraulic cylinder C including a cylinder 10 that is a cylinder and a piston rod 11 that is a shaft that is movably inserted into the cylinder 10. The first packing P1 and the second packing P2 are arranged in series between the cylinder 10 of the hydraulic cylinder C and the piston rod 11, and the first packing P1 provided inside the cylinder 10 is The seal member 20 faces the inside of the cylinder 10 and the backup ring 25 faces the sliding portion.

  Hereinafter, each part will be described in detail. As shown in FIG. 2, the hydraulic cylinder C includes a cylinder 10 that is a cylinder, a piston rod 11 that is a shaft that is movably inserted into the cylinder 10 via a piston 12, and a cylinder. 10 includes two oil chambers R1 and R2 partitioned by the piston 12, and ports 13 and 14 for supplying and discharging hydraulic oil into the oil chambers R1 and R2, respectively. It is connected to a hydraulic pump (not shown).

  Further, the cylinder 10 is formed in a bottomed cylindrical shape having an opening at the left end in FIG. 2, and a cylindrical bearing 15 for slidably supporting the piston rod 11 is fitted into the opening 11a at the left end. Further, annular grooves 16 and 17 are provided in series on the left inner periphery in FIG. 1 from the bearing 15 of the opening 11a, and an annular notch 18 is provided at the left end of the opening 11a. A first packing P1 is inserted into the annular groove 16, a second packing P2 is inserted into the annular groove 17, and a dust seal 19 is inserted into the notch 18.

  For example, when hydraulic oil is supplied to the oil chamber R1 via the port 13 and discharged from the oil chamber R2 via the port 14, the hydraulic cylinder S contracts, and conversely, the hydraulic cylinder S2 operates to the oil chamber R2. When the oil is supplied and the hydraulic oil is discharged from the oil chamber R1, the hydraulic cylinder C can extend, thereby exhibiting a function as a cylinder.

  Accordingly, high pressure and low pressure act on the first packing P1 and the second packing P2 provided in the gap between the piston rod 11 and the opening 11a depending on the moving direction of the piston rod 11.

  Subsequently, as described above, the first packing P1 is composed of the seal member 20 and the backup ring 25. Further, the seal member 20 is attached to the annular inner lip 21 and the cylinder 10 which are in sliding contact with the piston rod 11. An annular outer lip 22 that abuts the inner circumference of the formed annular groove 16 is provided. On the other hand, the backup ring 25 is formed in an annular shape, and an outer peripheral side end portion (seal member) of the inner lip 21 of the seal member 20. When it is captured as a whole 20, it becomes an inner peripheral side) and is integrated so as not to be separated.

  The term “integrated so as not to be separated” as used herein means that the seal member 20 and the backup ring 25 are integrated so as not to generate a gap. This is intended to exclude integration by mere fitting, press fitting, or the like that causes a gap between the ring 25 and the like.

  The term “inseparable” does not mean that separation is not caused even if an excessive force or chemical action is applied, but it does not mean that separation is not possible under the circumstances where the seal is used.

  As described above, in this case, the seal member 20 is formed in a U-packing shape, the opening 23 faces the inside of the cylinder 10, and the pressure in the oil chamber R <b> 1 of the cylinder 10 is opened to the opening. 23, the inner lip 21 and the outer lip 22 are pressed against the piston rod 11 and the annular groove 16, respectively, by this pressure to seal between the cylinder 10 and the piston rod 11.

  In this case, the backup ring 25 is arranged so as to face the outer periphery of the piston rod 11 as a sliding portion, and the inner lip 21 is deformed more than necessary by the pressure described above, and a gap between the piston rod 11 and the opening 11a. And the occurrence of excessive frictional resistance between the piston rod 11 and the inner lip 21 is prevented, and the deterioration of the sealing performance due to wear of the sealing member 20 is prevented.

  Here, the seal member 20 is made of a thermoplastic polyurethane-based resin, while the backup ring 25 is made of a polyamide-based resin such as nylon 12 and specifically includes an amide group. Those are preferred. The resin includes a resin composition.

  Then, after the seal member 20 is molded into a U-packing shape, a polyamide-based resin is injection-molded, and the backup ring 25 is fused to the seal member 20.

  Specifically, for example, an annular notch is provided in a portion where the backup ring 25 is fused at the left end of the inner lip 21 in FIG. 1 of the inner lip 21 of the seal member 20, and further, in the mold that forms the first packing P1. The sealing member 20 is inserted, and the polyamide resin, which is the material of the backup ring 25, is heated from about 200 degrees to about 300 degrees in the mold so that the backup ring 25 is integrated into the notch. Injection molding.

  Then, the thermoplastic polyurethane resin that is the material of the seal member 20 and the polyamide resin that is the material of the backup ring 25 are fused and integrated so as not to be separated. When the polyamide resin as the material contains an amide group, this amide group can chemically act on the thermoplastic polyurethane resin to increase the bonding strength compared to normal fusion, The seal member 20 and the backup ring 25 can be firmly joined and integrated.

  On the contrary, the backup ring 25 is first formed into a ring shape with a polyamide-based resin, and the thermoplastic polyurethane-based resin that is the material of the sealing member 20 is heated from about 200 degrees to about 230 degrees and then injection-molded and sealed. The member 20 and the backup ring 25 may be integrated.

  In addition, when the peel test of the first packing P1 was performed according to JIS K6250, when the nylon 12 containing an amino group heated to 200 degrees was injection-molded and heat-sealed to the thermoplastic polyurethane resin, Strips of thermoplastic polyurethane resin and nylon 12 (width 13-14mm) do not peel even at a tensile force of 450N (tests 5 times, error 30N, average 450N, the specimen breaks and no peeling is observed) The same material was bonded to this, and the same peel test was conducted, and even if it was peeled with a tensile force of 60 N (test number of times 5 times, error 30 N, average 60 N), Bonding strength is very high compared to bonding, welding, etc., and therefore, the sealing member 20 and the backup ring 25 are integrated by the above-mentioned fusion method. , Excessive oil pressure is advantageous in that there is no worry of peeling also act.

  Further, in the above description, the material of the seal member 20 is a thermoplastic polyurethane resin, and the material of the backup ring 25 is a polyamide resin. However, as another embodiment, the backup ring 25 has a higher hardness than the seal member 20. In setting the hardness to be hard, the material of the seal member 20 and the backup ring 25 may be a similar resin material.

  As a material of the seal member 20 and the backup ring 25 in other embodiments, specifically, for example, a thermoplastic polyurethane resin may be used, and the hardness of the seal member 20 may be A93 (standard standard JIS K6253 durometer A hardness). ) And the hardness of the backup ring 25 is preferably A98 (standard standard JIS K6253 durometer A hardness).

  The shapes of the seal member 20 and the backup ring 25 in the other embodiments are the same as those in the above-described embodiment, and the above-described implementation is also performed when the seal member 20 and the backup ring 25 are integrated. What is necessary is just to employ | adopt the manufacturing method similar to a form.

  Since the seal member 20 and the backup ring 25 that are made of the same resin material in this way are the same resin material, the fusion bonding strength between the seal member 20 and the backup ring 25 is increased. The possibility can be made lower.

  Further, when the backup ring 25 is made of a thermoplastic polyurethane resin, since it is generally softer than a polyamide resin, there is an advantage that the first packing P1 can be easily inserted into the annular groove 16. That is, when the first packing P1 is stored in the annular groove 16, the first packing P1 needs to pass through the opening 11a having an inner diameter smaller than the outer diameter of the first packing P1, and therefore the first packing P1 is bent. However, as described above, since the backup ring 25 formed of a soft thermoplastic polyurethane resin is more easily deformed, the first packing P1 can be easily inserted into the annular groove 16. It becomes.

  In turn, the second packing P2 is a U-packing provided with an annular inner lip 31 slidably contacting the piston rod 11 and an annular outer lip 32 contacting the inner periphery of the annular groove 17 formed in the cylinder 10. An annular plate-like backup ring 35 is fitted into the annular groove 17 on the outer side of the cylinder 10 which is the back side of the second packing P2.

  About this 2nd packing P2, what is necessary is just to select and select various materials in the range which is not inconvenient in sealing between the piston rod 11 and the cylinder 10, especially.

  Further, a dust seal 19 is inserted in the notch 18 to prevent dust and water from entering the cylinder 10.

  Now, in the seal structure of the sliding portion configured as described above, even if the relative movement of the piston rod 11 with respect to the cylinder 10, that is, the expansion and contraction of the hydraulic cylinder C is repeated for a long time, the first packing P1 is configured. Since the seal member 20 and the backup ring 25 are integrated so as not to be separated, the hydraulic oil does not enter and accumulate between the seal member 20 and the backup ring 25.

  Therefore, since the backup ring 25 is not separated from the seal member 20, the function of the sealing performance can be maintained, and the gap between the axial piston rod 11 and the cylindrical cylinder 10 is properly sealed. Is possible.

  That is, since the hydraulic oil does not enter and accumulate between the seal member 20 and the backup ring 25, the seal member 20 is pressed against the right side wall of the annular groove 16 in FIG. 1, it is possible to prevent the hydraulic oil in the space 40 from being inhibited from returning into the cylinder 10 without being pressed against the left side wall. Further, the piston rod shaft between the first packing P1 and the annular groove 16 can be prevented. By always ensuring a gap in the direction, the pressure in the oil chamber R1 of the cylinder 10 can always be received by the opening 23, and the inner lip 21 and the outer lip 22 are firmly attached to the piston rod 11 and the annular groove 16, respectively. By pressing, the sealing performance between the cylinder 10 and the piston rod 11 can be improved.

  For this reason, the hydraulic oil passing through the first packing P1 is not accumulated in the space 40 between the first packing P1 and the second packing P2, and the pressure in the space 40 does not increase abnormally, and the second packing P2 Is avoided from being melted and worn, so that the sealing performance of the second packing P2 is not hindered.

  That is, in the seal structure of the sliding portion, since the deterioration of the sealing performance of the first packing P1 and the second packing P2 can be prevented, the inside of the cylinder 10 is sealed even if the movement of the piston rod 11 is repeated for a long period of time. Can be maintained in a state.

  In addition, since the function of the first packing P1 as a buffer seal is maintained without deterioration over a long period of time, the sealing performance of the second packing P2 itself is also maintained over a long period of time, and as a result, both the packings P1 and P2 are maintained. The durability can be improved and the life can be extended.

  Further, since the pressure of the hydraulic oil acting on the inner lip 31 of the second packing P2 does not increase, the inner lip 31 is prevented from being pressed against the piston rod 11 with a force more than required for sealing, As a result, an excessive frictional force is prevented from being generated between the piston rod 11 and the second packing P2, and the smooth movement of the piston rod 11 is ensured.

  That is, the smooth expansion / contraction operation of the hydraulic cylinder C is ensured, and no energy is lost in driving the hydraulic cylinder C.

  When the seal member 20 and the backup ring 25 are integrated, the bonding strength is increased by the above-described fusion, and there is no fear of peeling between the seal member 20 and the backup ring 25, and the sealing performance in the first packing P1. However, as long as the necessary strength can be ensured, the integration may be performed by adhesion or welding.

  In this embodiment, since the seal structure of the sliding portion is embodied in the hydraulic cylinder C, annular grooves 16 and 17 are provided on the cylinder 10 side, and the first packings P1 and P2 are respectively inserted and inserted. However, when the annular groove is provided on the shaft side, since the sliding portion is on the cylinder inner peripheral side, a backup ring may be provided at the left end in FIG. 1 on the outer periphery of the outer lip 22 of the first packing P1. .

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

FIG. 3 is an enlarged vertical sectional view of a seal portion of a hydraulic cylinder in which a sliding portion seal structure of the present invention is embodied. It is a schematic longitudinal cross-sectional view of a hydraulic cylinder. It is a longitudinal cross-sectional view of the sealing structure of the conventional sliding part.

Explanation of symbols

10 cylindrical cylinder 11 axial piston rod 11a opening 12 piston 13, 14 port 15 bearing 16, 17 annular groove 18 notch 19 dust seal 20 seal member 21, 31 outer lip 22, 32 outer lip 23 opening 25, 35 backup ring 40 Space C Hydraulic cylinder P1 First packing P2 Second packing R1, R2 Oil chamber

Claims (7)

In the seal structure of the sliding portion that seals between the shaft and the cylinder with the first packing and the second packing arranged in series between the cylinder and the shaft that is movably inserted into the cylinder, The first packing provided on the inner side of the cylinder from the packing includes a seal member facing the inner side of the cylinder and a backup ring facing the sliding portion, and the seal member and the backup ring are integrated so as not to be separated. A sliding structure for a sliding portion, characterized by comprising: The seal structure for a sliding portion according to claim 1, wherein the seal member and the backup ring are integrated by adhesion, welding, or fusion. The seal member includes an annular inner lip that slidably contacts the shaft side and an annular outer lip that slidably contacts the cylinder side, and the backup ring is integrated with the outer peripheral end of the inner lip or outer lip of the seal member. The seal structure of the sliding part according to claim 1 or 2, characterized in that The sealing member is a resin member made of thermoplastic polyurethane resin, the backup ring is a resin member made of polyamide resin, and the sealing member and the backup ring are integrated by fusion. The seal structure of the sliding part according to claim 1 or 3. The seal member and the backup ring are resin members made of the same resin, and the backup ring is formed of a member harder than the seal member, and the seal member and the backup ring are integrated by fusion. The seal structure of the sliding part in any one of Claim 1 or 3. In the mold for molding the first packing, by inserting a seal member provided with a notch at the site where the backup ring is fused in advance, and heating and injecting the resin material forming the backup ring into the notch, 6. The seal structure for a sliding portion according to claim 4, wherein the seal member and the backup ring are integrated. The seal member and the backup ring are integrated by inserting a backup ring in advance into the mold for molding the first packing and heating and injecting the resin material forming the seal member into the mold. The seal structure of the sliding part according to claim 4 or 5, characterized by the above-mentioned.

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