JP4026640B2 - Piston cylinder sealing device - Google Patents

Description

  The present invention relates to a sealing device for a piston cylinder, and more particularly to a sealing device for a piston cylinder that can be suitably used for sealing a hydraulic cylinder that slides smoothly under high pressure using water as a working medium.

  As a working medium of the fluid working device, air, water, or the like is used, typically oil. In these fluid operation devices, various sealing devices are appropriately used depending on the operation medium. For example, for oil pressure, a so-called lip is provided on the sealing member to improve airtightness, and for air pressure, an R portion is provided at the tip of the sealing member to ensure smooth sliding.

  In fluid working equipment that has traditionally used oil as the working medium, change the working medium to water so that the outside of the working medium can be removed when disposing of this oil working equipment or dismantling / disassembling the fluid working equipment. It is possible to virtually eliminate environmental pollution and fires caused by spills, and to provide fluid-operated equipment that is environmentally friendly. In addition, when water is taken into consideration as a working medium, compared to general mineral oil, since the rigidity is high and bubbles are easily removed, there is virtually no delay in the operation of the device (volume elastic modulus: mineral oil 1000 to 1600 MPa, water 2000-2300MPa), and there is little change in viscosity due to temperature change, and there is little change in operation even at low temperatures, so that the performance of fluid operating equipment can be improved. In addition, since viscosity is low and viscosity change is low even at low temperatures, Because the pressure loss is small and the heat capacity is large (mineral oil 1890J / kg · K, water 4200J / kg · K), the tank capacity can be reduced, and water is more excellent than oil in terms of availability and price. Economics are also advantageous.

  However, in order to replace the working medium of hydraulic equipment that has been used so far with water and use hydraulic equipment, a hydraulic cylinder, for example, can withstand a high pressure such as 14 MPa, which is the working pressure of the hydraulic cylinder. It needs to be possible. In the following description, a case where the hydraulic device is a hydraulic cylinder is taken as an example.

  The hydraulic cylinder is considered to use stainless steel as a structural member because it needs to satisfy the corrosiveness and mechanical strength against water. The sealing member and sliding member of this hydraulic cylinder (hereinafter referred to as “sealing member”) It is conceivable to use a resin or a ceramic material that is compatible with stainless steel in an aqueous environment. That is, if the hydraulic cylinder is used with a rubber sealing member or the like that is commonly used for a hydraulic cylinder, rusting occurs early, the rigidity of the sealing member is small, the pressure resistance is insufficient, the sealing Since the friction coefficient of the member, etc. is large and the sliding resistance is large, it is easy to wear and leak, and the friction loss of the cylinder increases, and furthermore, the control amount of the cylinder becomes difficult due to the large amount of change in sliding resistance. This is because a problem is assumed. In addition, the surface tension of water is large, so wettability to the mating surface is poor, lubricity is poor, it is necessary to take anti-freezing measures to freeze at ambient temperatures below freezing, and water There are also problems such as deterioration due to discoloration, slimming and generation of bacteria. Furthermore, since there is little demand for the hydraulic system, there is a problem that the equipment cost becomes expensive.

  On the other hand, the sealing member made of resin also has poor sealing performance due to poor elasticity, and the hydraulic cylinder lubrication conditions are considerably strict compared with the hydraulic cylinder lubrication conditions. Wear tends to be promoted.

In view of this, Patent Document 1 discloses an invention in which a smoother slidability is ensured by making a cylinder tube of a hydraulic cylinder made of a polyolefin resin.
Patent Document 2 discloses an invention in which the entire cylinder tube of the hydraulic cylinder is made of resin, and a metal cylinder is fitted inside the cylinder tube to reduce weight, reduce size, and ensure corrosion resistance. Has been.

  Further, the applicant of the present invention previously described in Patent Document 3, as a sealing device for fluid pressure equipment such as a hydraulic cylinder or a pneumatic cylinder, in particular, a seal body made of rubber that can be crosslinked with a peroxide vulcanizing agent, On the sliding surface side of this seal body, the molecular weight is generally very large at 1 million or more, and ultra-high molecular weight polyethylene known for its excellent wear resistance, self-lubricating property, impact resistance property at low temperature, etc. A sealing device in which a coating layer made of UHMWPE) is combined without an adhesive is disclosed.

JP 2001-12415 A Japanese Patent Laid-Open No. 2003-4008 JP 11-325255 A

  According to the conventional techniques disclosed in Patent Documents 1 to 3, the target hydraulic cylinder itself can be improved, and the technical problem in replacing the hydraulic cylinder in the fluid operating device with the hydraulic cylinder is improved. The

  However, in these conventional techniques, the sealing structure between the piston and the cylinder constituting the hydraulic cylinder is hardly considered, and the sealing structure of the hydraulic cylinder or the pneumatic cylinder is merely used as it is. Is.

  For this reason, as described above, when it is intended to provide a hydraulic cylinder that is used under a pressure of 1 MPa or higher, particularly under a high pressure such as 14 MPa, the durability and sliding characteristics of the sealing member of the hydraulic cylinder are insufficient. There is a high risk of doing so. For this reason, it is necessary to provide a sealing device suitable as a sealing member for a hydraulic cylinder.

  In other words, the problem in changing the working medium of fluid working equipment that has used oil as the working medium to water is that the working medium, water, has a low viscosity, so that it is easy to leak and it is difficult to form a water film. Since it is difficult to form a liquid film and the lubricity is poor, the wear of the packing, which is a sealing member, is promoted, so that it is not possible to actually provide a fluid working device using water as a working medium.

  An object of the present invention is to provide a sealing device for a piston-type cylinder, and more specifically, in particular, water is used as a working medium and smoothly under a pressure of 1 MPa or more, particularly, a high pressure such as 14 MPa. It is another object of the present invention to provide a sealing device for a piston-type cylinder that has sufficient durability and can be suitably used for sealing a sliding hydraulic cylinder.

The present inventors have examined the material and shape of the sealing member for the piston cylinder sealing device that can solve the above-described problems.
The sealing member needs to be made of a material having self-lubricating properties because it does not cause changes in properties and dimensions due to water absorption or swelling, and formation of a water film cannot be expected. Examples of such a material include filled tetrafluoroethylene resin (PTFE), ultrahigh molecular weight polyethylene resin (UHMWPE), and rubber having self-lubricating properties. It is desirable to use ultra high molecular weight polyethylene resin (UHMWPE).

  In general, a primary seal in a seal system is intended to ensure that the cylinder is operated by sealing the working medium and shutting off the pressure. However, the primary seal is a small leak of water film (oil film). However, it hardly affects the operation of the cylinder.

  The primary seal piston is on both the pressure and non-pressure sides, the piston rod is on the pressure side, and the periphery of the sealing member is surrounded by water as the working medium, so it is relatively easy to maintain a water film. However, since water is poorly lubricated compared to oil, stick-slip phenomena (chatter due to self-excited vibration caused by changes in the compressibility of water and frictional force of the packing and sliding parts) are likely to occur. A sealing member composed of a sealing member and a supporting member (also referred to as “STN seal” as described later) is used.

  On the other hand, the sealing member of the secondary seal is naturally exposed to water leakage when the water film is thick because the water film is exposed to the outside. It is difficult to maintain a water film. If only the above-mentioned STN seal is used as the secondary seal, the sealing performance is insufficient, so it is difficult to control the water film, that is, to prevent water leakage to the outside. Therefore, along with the above-mentioned STN seal, the secondary seal can form a gentle contact surface pressure on the outer peripheral surface of the rod and keep grease or water in the recess by a plurality of annular projections with rounded lip tips. By using a pneumatic seal (also referred to as “GLY packing”) that can maintain lubricity by doing so, it becomes possible to thicken the water film and improve the lubrication state.

Also, a dust seal is used as a tertiary seal in order to prevent dust and the like from the outside and protect the packing and bearings inside the cylinder.
As a result of intensive studies based on the above knowledge, the present inventors have provided a plurality of sealing members in a piston-type cylinder having a piston and a piston rod accommodated in the cylinder and using water as a working medium. By specifically specifying the installation position, material, and structure of the sealing member, it can be suitably used for sealing a hydraulic cylinder that slides smoothly and with sufficient durability even under a high pressure of 14 MPa, for example. The present invention has been completed by discovering that it is possible to provide a sealing device for a piston-type cylinder capable of achieving the above.

The present invention is a sealing device for a piston-type cylinder having a piston and a piston rod accommodated in a cylinder and using water as a working medium, and a sealing member made of ultra-high molecular weight polyethylene and a sealing member on the inner surface of the cylinder A first sealing member attached to the outer surface of the piston, a sealing member made of ultra high molecular weight polyethylene, and a supporting member that urges the sealing member toward the outer surface of the piston rod. A rubber seal having a second sealing member mounted on the inner surface of the cylinder and a lip formed with a convex portion that contacts the outer surface of the piston rod, the third sealing member being mounted on the inner surface of the cylinder A sealing member and a resin-made fourth sealing member that is attached to the inner surface of the cylinder so as to contact the outer surface of the piston rod and prevents dust from entering. With combined viewed, the first sealing member, the second sealing member, a third sealing member and the fourth sealing member, together with the provided in this order in a direction from the piston to the piston rod, a second seal member in the region between the third sealing member, a piston-type cylinder is a third sealing member, characterized in Rukoto includes a drain port for preventing the growing pressure of the region by draining sealed water The sealing device.

  In addition, as disclosed in Patent Document 3 described above by the present applicant, a fluid pressure obtained by combining a coating layer made of ultrahigh molecular weight polyethylene (UHMWPE) on the sliding surface side of a rubber seal member without an adhesive. Equipment sealing devices are already known. However, not only in Patent Document 3, but also in Patent Documents 1 and 2, for example, the installation positions, materials, and structures of a plurality of sealing members provided in a piston cylinder using water as a working medium under a high pressure of 14 MPa, for example, Not suggested. By clarifying the significance of the present invention, a piston type that can be suitably used for sealing a sliding hydraulic cylinder smoothly and sufficiently with durability even under such a high pressure. A cylinder sealing device can actually be provided.

  According to the present invention, a piston-type cylinder that can be suitably used for sealing a hydraulic cylinder that slides smoothly under a pressure of 1 MPa or more, particularly a high pressure such as 14 MPa, in particular, using water as a working medium. A sealing device can be provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out a piston-type cylinder sealing device according to the present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view showing an example of the structure of a piston-type cylinder sealing device 1 according to the present embodiment. In FIG. 1, the lower half of the piston center line l is omitted.

  A sealing device 1 shown in FIG. 1 is a sealing device 1 for a piston-type cylinder 5 using water as a working medium. The piston-type cylinder 5 is a well-known and conventional one, and also in this example, it has a piston 4a that is accommodated in the cylinder 3 and constitutes an opposing sliding surface of the cylinder 3, and a piston rod 4b that is exposed to the outside.

  And this sealing device 1 makes the 1st sealing member 6, the 2nd sealing member 7, the 3rd sealing member 8, and the 4th sealing member 9 the direction (in FIG. 1) toward piston rod 4b from piston 4a. (In the direction from right to left). Then, the sealing members 6-9 which are the components of the sealing device 1 are demonstrated one by one below.

[First sealing member 6]
FIG. 2 is an explanatory view showing an extracted first sealing member 6 and a second sealing member 7 described later.

  As shown in FIGS. 1 and 2, the first sealing member 6 is mounted and accommodated by appropriate means in a groove portion 10 formed in an annular shape on the outer peripheral surface of the piston 4 a. The first sealing member 6 is composed of a seal member 11 and a support member (back ring) 12 and forms a piston seal. In the present specification, the first sealing member 6 including the seal member 11 and the support member 12 is also referred to as an “STN seal”.

  The seal member 11 is made of ultra high molecular weight polyethylene (UHMWPE). Here, “ultra high molecular weight polyethylene” has a very high molecular weight of generally 1 million or more, and is excellent in wear resistance, self-lubricating property, impact resistance at low temperature, and the like. Ultra high molecular weight polyethylene is commercially available on a normal sales channel. For example, Hi-Zex Million 240M (trade name) manufactured by Mitsui Petrochemical Co., Ltd. can be used.

  As described above, the material of the sealing member 11 of the sealing device 1 of the piston-type cylinder 5 using water as a working medium includes (a) that neither properties nor dimensions change due to water absorption or lubrication, and (b ) Since water film formation cannot be expected, it may be self-lubricating. Examples of such materials include filled tetrafluoroethylene resin (PTFE), ultrahigh molecular weight polyethylene resin (UHMWPE), and self-lubricating rubber. In the present invention, water is used as a working medium. Therefore, an ultra high molecular weight polyethylene resin (UHMWPE) having the best compatibility with water is used.

  The seal member 11 is formed in an annular shape having a rectangular cross section. The forming means may be a known means and is not limited to a specific means. When the outer peripheral surface of the seal member 11 contacts the inner peripheral surface 3a of the cylinder 3 as the contact surface 11a, the piston 4a and the cylinder 3 are sealed.

Unlike this example, the seal member 11 may be a composite seal in which only the contact surface 11a of the seal member 11 is made of ultrahigh molecular weight polyethylene.
On the other hand, the support member 12 is formed in an annular shape with a circular cross section by an elastic material such as rubber (NBR in this example). The support member 12 urges the seal member 11 toward the inner surface 3a side of the cylinder 3 by supporting the inner surface side surface of the seal member 11 (the surface formed at a position facing the contact surface 11a). To do. Thereby, the outer peripheral surface of the seal member 11 is in surface contact with the inner surface 3a of the cylinder 3, and the cylinder 3 and the piston 4a are sealed.

That is, although the periphery of the first sealing member 6 constituted by the seal member 11 and the support member 12 is surrounded by water, it is relatively easy to maintain a water film, but has poor lubricity compared to oil. Therefore, an STN seal was used in consideration of the possibility of stick-slip phenomenon.
The first sealing member 6 in the present embodiment is configured as described above.

[Second sealing member 7]
As shown in FIGS. 1 and 2, the second sealing member 7 is mounted and accommodated in a groove 3 b that is formed in an annular shape on the inner surface of the cylinder 3. That is, the 2nd sealing member 7 comprises the packing for rods with the 3rd sealing member 8 and the 4th sealing member 9 which are mentioned later. However, since the water film of the rod packing is exposed to the outside, if the water film is thick, water leakage naturally occurs. However, even if the water film is thin, the water evaporates and the lubrication state is further deteriorated. For this reason, it is difficult to maintain the water film on the rod surface. For this reason, it is difficult to ensure sufficient sealing performance only with the second sealing member 7, and it is impossible to control the water film, that is, to prevent water leakage to the outside.

  Therefore, in the present invention, even if some water leakage is allowed by the second sealing member 7, the pressure inside the cylinder 5 is surely cut off, and a water film is formed by the third sealing member 8 described later. Be sure to control to prevent water leaks.

  Similarly to the first sealing member 6, the second sealing member 7 is also configured by an “STN seal” including a sealing member 11 and a support member 12. The support member 12 urges the seal member 11 toward the outer surface side of the piston rod 4 b by supporting the outer surface side of the seal member 11. Thereby, the inner peripheral surface of the seal member 11 is in surface contact with the outer surface of the piston rod 4b. Thereby, the 2nd sealing member 7 ensures the sealing performance of piston 4a with respect to the cylinder 3 with the 3rd sealing member 8 mentioned later.

The second sealing member 7 in the present embodiment is configured as described above.
3 and 4 are explanatory views showing modified examples 6-1, 6-2, 7-1, and 7-2 of the first sealing member 6 and the second sealing member 7 described above.

  In the modified examples 6-1 and 7-1 shown in FIG. 3, two protrusions 13 are formed annularly on the contact surface 11 a of the seal member 11. Thereby, since a contact surface pressure can be raised, sealing performance can be improved. Further, by providing directionality to the protrusion 13, it is possible to form a thinner water film from the pressure side to the non-pressure side (between the second sealing member 7 and the third sealing member 8). The water film leaking to the pressure side can be easily drawn to the pressure side. In this specification, the modified examples 6-1 and 7-1 are also referred to as “SMJ seals”.

  On the other hand, in the modified examples 6-2 and 7-2 shown in FIG. 4, the support member 12 having a rectangular cross section and an annular shape is used, and the seal member 11 has a circular cross section. The one formed in an annular shape was used. Thereby, a gentle contact stress distribution can be obtained. In this specification, it is also referred to as “ST seal”.

  When it is particularly necessary to prevent the working medium from leaking to the outside, the first sealing member 6 and the second sealing member 7 are STN seals or SMJ seals in which the seal member 11 and the support member 12 are combined. Alternatively, various known rubber seals may be used in combination with the ST seal. Thereby, the sealing performance of the piston 4a with respect to the cylinder 3 can be further improved, and it is possible to reliably prevent the water as the working medium from leaking to the outside.

The second sealing member 7 in the present embodiment is configured as described above.
[Third sealing member 8]
FIG. 5 is an explanatory view showing the third sealing member 8 in the present embodiment.

  As shown in FIGS. 1 and 5, the third sealing member 8 is mounted and accommodated in a groove 3 c formed in an annular shape on the inner surface of the cylinder 3. The third sealing member 8 is a packing having a lip 8a formed with a convex portion 8b that contacts the outer surface of the piston rod 4b, and is well known and commonly used as a pneumatic packing. In this specification, it is also referred to as “GLY packing”.

  The tip 8d of the lip 8a has a chamfered curved surface shape or a straight planar shape, whereby a gently small contact stress distribution can be formed on the outer peripheral surface of the piston rod 4b. Moreover, since the GLY packing 8 can hold | maintain grease or water in the recessed part 8c, it can ensure lubricity.

  Moreover, as a material of the 3rd sealing member 8, since it is generally used by 1 Mpa or less, it is desirable to use the thing of hardness Hs70. In GLY packing, because it is Hs73, a rubber with a special composition having a self-lubricating action is further used in the material itself. Thereby, sufficient lubricity and slidability can be ensured.

  According to the knowledge of the present inventors, as this third sealing member 8, since the lip tip has a sharp shape, it is easy to scrape out a water film and hardly cause external leakage, and a hydraulic SNY packing made of NBR is used. Due to the poor lubrication state, the wear of the SNY packing is promoted and the desired durability cannot be obtained.

  Therefore, in the present invention, as the third sealing member 8, a water film having a thickness larger than that of the water film formed by the SNY packing can be formed, and in order to reliably prevent external leakage, the GLY packing is used. Is used.

The third sealing member 8 together with the second sealing member 7 ensures the sealing performance of the piston 4 a with respect to the cylinder 3.
The third sealing member 8 in the present embodiment is configured as described above.

[Fourth sealing member 9]
FIG. 6 is an explanatory view showing the structure of the fourth sealing member 9.
The fourth sealing member 9 includes a seal member 13 and a support member (buckling) 14. In the present specification, the fourth sealing member 9 is also referred to as “SDR scraper”.

  The seal member 13 is ultra high molecular weight polyethylene (UHMWPE), and the support member 14 is an O-ring made of NBR. PTFE may be used for the seal member 13, but UHMWPE is more compatible with water. Further, since the SMD scraper 9 includes the seal member 13 having two contact portions 13a and 13b having a flat contact surface projecting, the contact surface stress distribution is gentle.

  Thereby, the 4th sealing member 9 which consists of a SMD scraper is attached to the inner surface of the cylinder 3 so that it may contact the outer surface of the piston rod 4b, as shown in FIG.1 and FIG.6, and prevents intrusion of dust.

  FIG. 7 is an explanatory view showing the structure of an SDR seal 9-1 which is a rubber seal member having lips 9a and 9b. The SDR seal 9-1 is an NBR dust seal commonly used in general hydraulic cylinders. The lip 9a prevents dust from entering, and the lip 9b provides an oil seal.

  According to the knowledge of the present inventors, when the SDR seal 9-1 is used as the fourth sealing member 9, since the lip 9a has a sharp edge, the lubricity deteriorates and wears down significantly. Durability cannot be secured.

  For this reason, in the present embodiment, it is determined that dust sealing using the SDR seal 9-1 made of a single rubber is difficult, and the seal member 13 and the support member (back ring) 14 are configured as described above. An SMD scraper 9 was used.

  While maintaining sufficient durability, the SMD scraper 9 can prevent the entry of dust and the like by the edge 13c on the atmosphere side, and can form a thin water film by the edge 13d on the packing side, thereby preventing water leakage to the outside. it can.

The fourth sealing member 9 prevents dust and the like from the outside, and protects the packing and the bearing inside the cylinder.
The fourth sealing member 9 in the present embodiment is configured as described above.

  In addition, the codes | symbols 16-19 in FIG. 1 show a bearing. The bearings 16 to 19 are for preventing eccentricity by receiving the load of the piston rod 4b, and are generally a phenol resin containing cloth, polyamide resin, metal (a type in which PTFE is baked on a metal; for example, Daido Metal) DU bushing of Kogyo Co., Ltd.) is used, but cloth-containing phenolic resins and polyamide resins cannot be used because of their high water absorption. Therefore, it is desirable that the bearings 16 to 19 also use rings made of ultrahigh molecular weight polyethylene UHMWPE. However, since plastic bearings may have a large backlash due to dimensional accuracy, the number of bearings may be increased, and metal bearings with anti-rust treatment or countermeasures on the hydraulic side ( It is desirable to use a DU bush.

  Reference numeral 21 denotes a water drain port. The drain port 21 is for the third sealing member 8 to drain the sealing water. As a result, the pressure increases between the second sealing member 7 and the third sealing member 8, and the third It prevents that the sealing member 8 is pressurized and the durability is impaired. However, if a seal that can easily draw the water film leaking to the non-pressure side, such as the “SMJ seal”, into the pressure side is used for the second sealing member 7, the drain port may or may not be installed. good.

  As described above, in the sealing device 1 of the present embodiment, the sealing members 11 of the sealing members 6 and 7 are made of ultrahigh molecular weight polyethylene having a friction coefficient smaller than that of rubber. Therefore, the first and second sealing members 6 and 7 are used. The sliding resistance can be reduced.

  Further, in the sealing device 1 of the present embodiment, since the STN seal including the sealing member 11 made of ultra high molecular weight polyethylene and the support member 12 made of rubber is used, the amount of change in sliding resistance is small and stable. Can be maintained.

  Further, in the sealing device 1 of the present embodiment, since the STN seal including the sealing member 11 made of ultra high molecular weight polyethylene and the support member 12 made of rubber is used, the durability of the sealing members 6 and 7 is improved and the sealing performance is improved. Can be improved.

  As a result, according to the present embodiment, water is used as a working medium, and it can be suitably used for sealing the sliding hydraulic cylinder 5 smoothly and with sufficient durability under a high pressure of 14 MPa, for example. The piston type cylinder sealing device 1 that can be provided has been provided.

Furthermore, the present invention will be described with reference to examples.
In the sealing device 1 according to the present invention shown in FIGS. 1 to 6, the third sealing member 8 and the fourth sealing member 9 were appropriately changed, and a durability test was performed in a state where a hydraulic pressure of 14 MPa was applied as a working medium. . The minimum operating pressure was measured as the pressure when the piston 4a was operated by supplying water into the cylinder 3 from one port. The specifications of the sealing device 1 are listed below together with the measurement conditions.

Dimensions of cylinder 3: cylinder tube diameter 50 mm, piston rod diameter 28 mm, cylinder stroke 300 mm
Pressure: 14MPa
Cylinder speed: 150mm / sec
Water temperature: 37.5-40 ° C

  FIG. 8 is an explanatory view showing a rubber hydraulic packing 20 (referred to as SNY packing) in which the third sealing member 8 is replaced. The measurement results of the minimum operating pressure are summarized in Table 1 together with the test conditions.

  As can be seen from the results shown in Table 1, the fourth sealing member was advantageous in that the rubber SDR scraper had a smaller sliding resistance than the resin SMD scraper.

  Thus, in order to reduce the sliding resistance, a rubber SDR scraper is advantageous as the fourth sealing member, but the durability test was performed only for A and B in Table 1 in consideration of the durability. . The results are summarized in Table 2.

  As can be seen from the results shown in Table 2, according to the piston-type cylinder sealing device 1 according to the present invention in which the third sealing member 8 is a GLY packing and the fourth sealing member 9 is an SMD scraper, It can be seen that the durability has been significantly improved.

  Therefore, according to the present invention, water is used as a working medium, and it seals a sliding hydraulic cylinder smoothly and sufficiently under a pressure of 1 MPa or more, particularly at a high pressure such as 14 MPa. A piston-type cylinder sealing device 1 that can be suitably used can be provided.

It is a longitudinal cross-sectional view which shows an example of the structure of the sealing apparatus of the piston type cylinder which concerns on embodiment. It is explanatory drawing which extracts and shows a 1st sealing member and the 2nd sealing member mentioned later. It is explanatory drawing which shows the modification of a 1st sealing member and a 2nd sealing member. It is explanatory drawing which shows the modification of a 1st sealing member and a 2nd sealing member. It is explanatory drawing which shows the 3rd sealing member in embodiment. It is explanatory drawing which shows a 4th sealing member. It is explanatory drawing which shows the structure of the 4th sealing member in the sealing device shown in FIG. It is explanatory drawing which shows the rubber-made SNY packing which substituted the 3rd sealing member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing device 3 Cylinder 3a Inner surface 3b, 3c Groove part 4a Piston 4b Piston rod 5 Piston type cylinder 6, 6-1, 6-2 First sealing member 7, 7-1, 7-2 Second sealing member 8 First Third sealing member 8a Lip 8b Convex portion 8c Concave portion 8d Tip 9 Fourth sealing member 9a, 9b Lip 9-1 SDR seal 10 Groove portion 11 Seal member 11a Contact surface 12 Support member 13 Seal member 13a, 13b Contact portion 13c Edge 13d Edge 14 Support members 16 to 19 Bearing 20 Hydraulic packing 21 Drain port

Claims (1)

A piston-type cylinder sealing device having a piston and a piston rod accommodated in a cylinder and using water as a working medium,
A seal member made of ultra high molecular weight polyethylene, and a support member that urges the seal member toward the inner surface of the cylinder, and a first sealing member attached to the outer surface of the piston;
A seal member made of ultra high molecular weight polyethylene, and a support member that urges the seal member toward the outer surface of the piston rod, and a second sealing member attached to the inner surface of the cylinder;
A rubber packing having a lip formed with a convex portion in contact with the outer surface of the piston rod, and a third sealing member attached to the inner surface of the cylinder;
In combination with a fourth sealing member made of resin that is attached to the inner surface of the cylinder so as to contact the outer surface of the piston rod and prevents the intrusion of dust ,
The first sealing member, the second sealing member, the third sealing member, and the fourth sealing member are provided in this order in the direction from the piston toward the piston rod,
A drain port is provided in a region between the second sealing member and the third sealing member to prevent an increase in pressure in the region by draining water sealed by the third sealing member. A sealing device for a piston-type cylinder.

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