JP2008082555A - Piston packing for air cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston packing for an air cylinder, having stable self-lubricating performance to allow the use with no oil supplied for a long period without being influenced by temperature conditions. <P>SOLUTION: The piston packing is formed of an elastic material 1b with its outer and inner peripheral faces in conical shapes. It has a truncated cone shaped part formed with a closed end at the small diameter end. It is continuously formed of a self-lubricating material 1a in a range from the upper face outer peripheral portion of the truncated cone shaped part to the truncated cone shaped outer peripheral face and the lower face outer peripheral portion. A round-off is given to each of an intersection between the upper face outer peripheral portion of the truncated cone shaped part and the truncated cone shaped outer peripheral face and an intersection between the truncated cone shaped outer peripheral face and the lower face outer peripheral portion. The round-off given to the intersection between the truncated cone shaped outer peripheral face and the lower face outer peripheral portion is put in contact with the inner face of the cylinder to prevent the separation of the self-lubricating material 1a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piston packing for an air cylinder.

  A packing is used for the piston for the air cylinder. For example, the contactor of the main circuit control device for railway vehicles uses various shapes integrally molded with rubber-based elastic material, and oil is used for lubrication of the sliding part with the cylinder. Therefore, regular refueling is necessary. In the case of making this non-lube, it is assumed that the cylinder is made of a self-lubricating material.

  Further, as described in Patent Document 1, the sliding portion with the cylinder is formed by molding a self-lubricating resin into a ring shape having a U-shaped cross section, and rubber is provided inside the U-shaped cross section. There is a type that uses a ring made of metal and is inserted into a groove provided in the piston.

  A ring that uses a metal spring material instead of rubber has less creep deformation than rubber and is excellent in durability. This type has a feature that it can be used without lubrication regardless of the material of the cylinder because the sliding part with the cylinder is a self-lubricating material.

  In the above packing, a lubricating body and an elastic body are fitted and fixed. As another example, as shown in Patent Document 2, for example, an annular ring having excellent lubricity is provided on the outer peripheral surface of a piston packing made of a rubber material or a resin material. There is a type in which the seal member is cast and mounted.

Japanese Utility Model Publication No. 1-154365 Japanese Utility Model Publication No. 56-87603

  (1) On the other hand, the above-mentioned lubrication problem can be solved with a combination packing of a ring and a rubber ring molded from a lubricious material. However, the airtightness of the packing and the cylinder is caused by elastic deformation during the volume compression of the rubber ring, Since the expansion rate of the tetrafluoroethylene resin molded product, which is a lubricant, is larger than that of a metal material, the volume compression ratio changes greatly when the temperature changes. At low temperatures, the volume compression ratio decreases, causing gas leakage. At high temperatures, the compressibility increases, the frictional resistance increases, and the temperature fluctuation of the operating time of the apparatus is large.

  Also, in the case of using a metal spring material instead of the rubber ring, there is a possibility that the metal spring part may be exposed and contact the cylinder when the lubricant is worn, and the cylinder may be damaged. It wasn't. In this case, since the metal spring cannot keep airtight with the cylinder, there is a disadvantage that the operation is instantaneously disabled.

  (2) In the case where the lubricating resin is molded in an annular shape and is cast into an elastic body, the expansion of the packing diameter is restrained by the resin material molded in the annular shape, so that the pressing force against the cylinder wall surface is secured. In order to achieve this, it is necessary to give a large allowance from the inside.

  However, a material generally used as a lubricating resin and a rubber material have greatly different creep characteristics and elasticity, and if a large elastic force is applied from the beginning, the lubricating resin on the outer peripheral side creeps and extends. When mounting on the cylinder, a force to reversely reverse is applied, but once the material has been creeped and extended, the material does not return to its original shape, and the outer periphery tends to wrinkle, causing air leakage.

  The above problem can be solved if the elastic force is applied after assembling by another member such as a pressing plate, but the point that the number of parts increases and the cost is not considered is not taken into consideration.

  In addition, it has been conventionally known that the end surface of the contact portion between the cylinder and the packing can be rounded so that the contact can be made into a line contact, contributing to stabilization of the starting frictional resistance. As for the shape of the end surface portion between the elastic body and the elastic body, the conventional shape can only round the thickness of the lubrication material on the outer peripheral side, so that the effect of the roundness on the wear is small.

  An object of the present invention is to provide a piston packing for an air cylinder that can be used without lubrication for a long period of time without being affected by temperature conditions and having a stable self-lubricating property.

  In order to achieve the above object, in the present invention, the outer peripheral surface and the inner peripheral surface are formed into a conical shape by using an elastic material, and are formed into a truncated cone shape having a closed end at a small diameter end thereof. A self-lubricating material is bonded to the outer peripheral surface of the conical section and is molded in one piece. The air cylinder is mounted in the cylinder so that it receives air pressure inside the frustoconical section and can be moved by compressed air for operation. In the air cylinder piston packing used for the piston part for the air cylinder, it is continuously formed of a self-lubricating material from the outer peripheral surface of the frustoconical part to the outer peripheral surface of the conical shape and the outer peripheral surface of the lower surface. A round is provided at the intersection with the conical outer peripheral surface and the intersection between the conical outer peripheral surface and the lower outer peripheral portion, and the roundness provided at the intersection between the conical outer peripheral surface and the lower outer peripheral portion is in contact with the inner surface of the cylinder. It had adopted a configuration which is adapted to.

  Here, a hole for attachment to the piston is formed at the center of the closed end of the truncated cone portion, and a metal spacer is attached to the hole, thereby preventing creep deformation of the elastic material when attached to the piston by tightening. Can do.

  The present invention has the following effects.

  (1) Since the frictional resistance between the piston packing and cylinder sliding part is low and stable, there is little change in operating time and the wear of the packing is kept small, so there is no need to change the lubricating oil frequently. Because it can be used without lubrication until the wear life of the packing, maintenance work can be omitted and maintenance costs can be reduced.

  In the case of pneumatic equipment for vehicles, there is an effect that what has conventionally been required to be refueled every 2 to 3 years can be used continuously without maintenance for 6 to 7 years.

  (2) Despite the use of a low friction material for the packing as described above, there are few air leaks and the tightness is not as strict as the O-ring, and airtightness is maintained by gas pressure, so a wide range of temperature conditions There is an effect that can cope with.

  (3) No special processing is required on the cylinder side, and maintenance regression can be easily extended by simply replacing the packing with the one of the present invention. For the user, there is no need to change the maintenance period between old and new, and the maintenance process can be unified.

  (4) Since wear of the packing is small and the operation time is stable, when several control switches are operated in conjunction with each other, there is little sequence error, and contact arcing and current fluctuation due to an abnormal sequence are eliminated. In the case of multiple simultaneous circuit breaker breaks, uneven contact wear occurs due to variations in the break operation time, but because the operation time is stabilized by the air cylinder of the present invention, the contact wear unevenness is small, and the maintenance regression extension of the contact is possible. There is an effect that can be achieved.

  An embodiment of the present invention will be described below. In FIG. 1, the piston packing 1 is formed in a truncated cone shape, and a self-lubricating material, for example, a mixed molding material 1a of 4 fluorinated ethylene resin and a filler is formed on the outer periphery of the truncated cone shape from the upper surface of the truncated cone. It is formed continuously from the side and bottom.

  An elastic material suitable for the temperature range to be used, such as nitrile rubber 1b, is formed on the inside of the truncated cone, and both are molded and bonded together in a mold. A hole 2 for fixing the packing 1 to the piston is provided in the center, and a spacer 2 made of metal or the like is attached to prevent creep deformation of the elastic material against tightening. As shown in FIG. 2, a piston rod 4 is penetrated through a central hole 3 a provided in the central portion of the cylinder 3 so as to be movable in the axial direction, and a piston 5 and a piston packing 1 are disposed at the inner surface side end portion of the piston rod 4. Is fixed with a nut 8 together with a plain washer 6 and a gasket 7.

  The end of the piston rod 4 opposite to the piston 5 is connected to a contact portion for giving an operating force so as to transmit the air pressure received by the piston. The contact portion fixes the movable contact 17 and the breaking contact 19 to the contact base 20, and is fixed to the support base 23 so as to be rotatable around the rotation shaft 21, and receives a rotational force in the clockwise direction shown in the figure by the contact spring 22. Yes. The support base 23 is fixed to the insulating joint 9. A fixed contact 18 is provided facing the movable contact.

  The inner surface sliding portion 3 b of the cylinder 3 is smoothly finished by honing polishing, plating, etc., and the piston packing 1 side is hermetically sealed by a lid 10 and a gasket 11. The cylinder 3 has an air supply hole 13, and an operation gas is supplied and exhausted by an electromagnetic valve device 12 into an airtight chamber 16 surrounded by the packing 1, the cylinder 3 and the lid 10.

  On the opposite side of the piston 5 from the packing 1, a return spring 14 is provided between the cylinder 3 and the piston 5, and a force in the direction opposite to the force by the operating gas is applied to the piston 5. An exhaust hole 15 is provided on the piston rod 4 side of the cylinder 3 in order to relieve back pressure generated on the side opposite to the operation gas when the piston operates. The operation of the embodiment thus configured will be described.

  In FIG. 2, the electromagnetic valve device 12 is operated, and the operating gas is supplied into the airtight chamber 16 through the air supply hole 13 of the cylinder 3. When the pressure in the hermetic chamber increases and the force received by the packing exceeds the resultant force of the spring 14, the frictional resistance, and the weight, the piston 5 is moved upward in the drawing.

  At this time, the operating gas tries to enter the chamber on the opposite side from the contact portion between the packing 1 and the cylinder 3, but the packing 1 is pressed against the wall surface of the cylinder due to the deflection of the elastic body of the packing, and the operating air pressure is Since it acts in the direction which spreads an umbrella, the force which presses the packing 1 becomes large, so that gas pressure increases, and operation gas does not leak.

  3, the piston rod is pushed upward from the state shown in FIG. 2, the fixed contact 18 and the movable contact 17 come into contact with each other, and the operation of the piston stops. The piston receives a downward force in the figure due to the reaction force of the return spring 14 and the contact spring 22 and gravity, but the state of FIG. 3 is maintained as long as the operating gas force is supplied.

  Next, when the solenoid valve device 12 is switched and the operating gas is shut off and the gas in the hermetic chamber is discharged through the air supply hole 13, the gas pressure in the hermetic chamber 16 decreases, and the force received by the piston packing 1 is changed to the spring. When the force of 14, the contact spring reaction force, and the resultant force of gravity are less than the total force, they move downward in the figure and return to the state of FIG. 2.

  At this time, if the frictional resistance between the packing 1 and the cylinder 3 is large, the time from when the solenoid valve 12 is switched to when the piston starts to move becomes long. Also, the time from the start of movement to the return to the state of FIG. 2 becomes longer as the frictional resistance increases, but the frictional resistance is low and stable because the contact portion between the packing and the cylinder is made of a self-lubricating material. Therefore, the return time from the state of FIG. 3 to the state of FIG. 2 is also short and stable.

  According to the embodiment, since the packing is formed into a truncated cone shape, the inside of the cone is made of an elastic material and the outside is made of a self-lubricating material, the frictional force between the cylinder wall surface and the packing can be reduced, and the inner elastic The material keeps the packing tightly attached to the cylinder surface and keeps the cylinder airtight. Since it has a conical shape, when operating air pressure is applied to the inside of the packing, the packing receives a force in the spreading direction and presses the seal portion against the cylinder, so that even if the operating air pressure increases, it does not leak.

  In addition, the pressing force to the cylinder is generated when the packing is assembled into the cylinder, so there is no need for extra pressure due to the inner elastic material before assembly, no self-lubricant creep occurs, and the cap shape As a result, the diameter continuously changes in the height direction of the shade, so that the outer periphery does not become wrinkled even when incorporated in the cylinder, and contact can be made at an optimum diameter portion, and there is no risk of air leakage.

  Further, since the end surface of the contact portion of the packing with the cylinder is rounded, the contact portion becomes linear and is not easily affected by wear, so that a stable starting frictional force can be maintained over a long period of time.

  Furthermore, when used in this pneumatically operated contactor for packing vehicles, it is possible to maintain a stable operation time over a long period of time, without disturbing the control sequence of the electric vehicle, and extending the return of maintenance. This has the effect of reducing maintenance costs such as saving labor costs and streamlining by unifying maintenance regression with other devices.

Cross section of piston packing for air cylinder of the present invention Sectional drawing of the air operation type contactor using the piston packing for air cylinders of this invention Sectional drawing which shows the contact contact state of the air operation type contactor shown in FIG.

Explanation of symbols

1a Self-lubricating material 1b Elastic material

Claims (2)

Using an elastic material, the outer peripheral surface and the inner peripheral surface are conical, and are formed into a truncated cone shape having a closed end at the small-diameter end, and a self-lubricating material is applied to the conical outer peripheral surface of the truncated cone portion. In piston packing for air cylinders, which are integrally molded and mounted in a cylinder so as to receive air pressure inside the frustoconical part and are used for piston parts for air cylinders that can be moved by compressed air for operation ,
A continuous surface formed of a self-lubricating material from the upper surface outer peripheral portion of the frustoconical portion to the conical outer peripheral surface and the lower surface outer peripheral portion; and the intersection of the upper surface outer peripheral portion and the conical outer peripheral surface and the conical outer peripheral surface; A piston packing for an air cylinder, characterized in that a roundness is provided at an intersection with an outer periphery of a lower surface, and the roundness provided at the intersection between the outer peripheral surface of the conical shape and the outer periphery of the lower surface is brought into contact with an inner surface of a cylinder.   The piston packing for an air cylinder according to claim 1, wherein a hole for attachment to the piston is formed in the center of the closed end of the truncated cone portion, and a metal spacer is attached to the hole.

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