JP5338695B2 - Fluid pressure cylinder dust removal mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve improvement in durability while achieving smooth operation of a piston including a piston rod by preventing dust deposited on the piston rod from entering into a cylinder body by surely removing the dust in a fluid-pressure cylinder. <P>SOLUTION: A fluid-pressure cylinder 10 is configured as follows. A rod cover 14 is provided with a sub-port 44 supplied with pressure fluid. The pressure fluid supplied to the sub-port 44 is supplied to an annular groove 40 facing a piston rod 18 and mounted with rod packing 42. The pressure fluid is circulated to the inner-peripheral side through a passage 64 formed in the rod packing 42, and is introduced into a space 66 provided against the outer-peripheral face of the piston rod 18. By this, dust or the like deposited on the outer-peripheral face of the piston rod 18 is blocked by the space 66 so as to prevent the dust from entering into the side of a cylinder tube 12. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a dust removing mechanism of a fluid pressure cylinder for preventing dust from entering the inside of a fluid pressure cylinder that displaces a piston along an axial direction under a pressure fluid supply action.

  2. Description of the Related Art Conventionally, a fluid pressure cylinder having a piston that is displaced under the action of supplying a pressure fluid has been used as a conveying means for a workpiece or the like.

  In such a fluid pressure cylinder, a piston is slidably provided in a cylinder chamber defined inside a cylindrical cylinder body, and a head cover and a rod cover are respectively attached to both ends of the cylinder body. The room is blocked. Further, an axial piston rod is connected to the piston, and is supported so as to be displaceable by being inserted through a rod cover (see, for example, Patent Document 1).

JP 2000-740007 A

  In such a fluid pressure cylinder, when the piston is displaced to the rod cover side, the piston rod protrudes to the outside through the rod cover and is exposed, so that dust or the like adheres to the outer peripheral surface of the piston rod. There is. When the piston is again displaced toward the head cover and the piston rod is pulled into the cylinder tube, dust or the like attached to the outer peripheral surface of the piston rod is removed by a scraper provided inside the rod cover.

  However, when the above-mentioned dust is a fine particle such as powder, or a liquid such as water or a solvent, it is difficult to completely remove the dust with a scraper, and the remaining dust is contained in the cylinder tube together with the piston rod. There is a concern that the dust may enter a gap and cause malfunction due to, for example, entering between the piston rod and the rod packing and the bearing, or between the cylinder tube and the piston.

  The present invention has been made in consideration of the above-mentioned problems, and by reliably removing dust adhering to the piston rod and preventing entry into the cylinder body, the piston including the piston rod operates smoothly. An object of the present invention is to provide a dust removing mechanism for a fluid pressure cylinder that can be improved in durability and improved in durability.

In order to achieve the above object, the present invention provides a cylinder body having a set of ports to which pressure fluid is supplied and a cylinder chamber into which the pressure fluid is introduced from the ports.
A piston provided inside the cylinder chamber so as to be displaceable along the axial direction;
A piston rod supported by the cylinder body, connected to the piston rod, and displaced so as to protrude outside the cylinder body;
A rod packing provided in the cylinder body and in sliding contact with the outer peripheral surface of the piston rod;
Dust entry preventing means for supplying the pressure fluid toward the piston rod and preventing dust adhering to the piston rod from entering the cylinder body;
With
The dust entry preventing means includes a holding portion that is provided between the rod packing and the piston rod and that is supplied and held with the pressure fluid, and a supply portion that supplies the pressure fluid to the holding portion. It is characterized by.

  According to the present invention, the fluid pressure cylinder further includes dust entry preventing means for preventing dust adhering to the piston rod from entering the cylinder body, and the dust entry preventing means is configured to cause the pressure fluid to flow toward the piston rod side. It is comprised from the supply part supplied toward and the holding | maintenance part by which the supplied said pressure fluid is hold | maintained. When the piston rod protruding outside the cylinder body is displaced in the direction of being accommodated inside the cylinder body under the displacement of the piston, the dust that has entered the holding portion together with the piston rod is retained. The pressure fluid held in the part prevents the entry, and even when it enters the holding part, the pressure fluid surely discharges it to the outside.

  Therefore, it is possible to reliably prevent dust adhering to the piston rod from entering the inside of the cylinder body through between the rod packing and the piston rod, and the operation of the hydraulic cylinder which is a concern when the dust enters. Defects are reliably avoided. As a result, the piston and the piston rod can always be smoothly displaced, and the durability of the fluid pressure cylinder can be improved.

  In addition, for example, when the dust is fine particles such as powder or liquid such as water and solvent that are difficult to completely remove with a scraper or the like in a conventional fluid pressure cylinder, the atmospheric pressure is maintained in the holding unit. On the other hand, the entry can be reliably and easily blocked by the high-pressure fluid, which is more preferable.

  Further, the supply portion is provided at an end portion of the cylinder body and provided at a rod cover that supports the piston rod so as to be displaceable along the axial direction, and a communication path that communicates the supply port and the holding portion. It is good to have.

  Furthermore, the supply unit may include a switching mechanism that selectively supplies the pressure fluid supplied to any one of the set of ports to the holding unit.

  Furthermore, the switching mechanism is provided at a rod cover provided at an end of the cylinder body and movably supports the piston rod along the axial direction, and is switched under a pressure fluid supply action, and the switching valve. It is preferable to provide a communication path that communicates either one of the ports and the holding portion with the displacement action.

  Further, the communication path may penetrate from the outer peripheral surface of the rod packing toward the inner peripheral surface and communicate with a holding portion provided so as to face the inner peripheral surface.

  Furthermore, it is good to provide multiple communicating paths along the circumferential direction of the rod packing formed cyclically | annularly.

  Furthermore, the holding portion includes an inner peripheral surface of the rod packing, a lip portion that is provided on one side surface of the rod packing and that is in sliding contact with the outer peripheral surface of the piston rod, and is formed on the inner peripheral surface of the piston rod. It is good to make it the space enclosed by the seal | sticker part which contact | abuts, and the outer peripheral surface of the said piston rod.

  Furthermore, the rod cover may have a hole through which the piston rod is inserted, and the hole may be provided with a dust capturing member capable of capturing and holding dust.

  Further, the rod cover may have a hole portion through which the piston rod is inserted, and a lubrication holding member for lubricating the piston rod may be provided in the hole portion.

  Furthermore, the rod cover may be provided with a discharge port that allows the hole portion and the outside to communicate with each other and discharge dust to the outside.

  Furthermore, the rod packing may be provided with a pressure reducing mechanism capable of reducing the pressure of the pressure fluid flowing to the piston rod side.

  According to the present invention, the following effects can be obtained.

  That is, when the piston rod protruding outside the cylinder body is displaced in a direction to be accommodated inside the cylinder body under the displacement action of the piston, dust that tries to enter the holding portion together with the piston rod is The pressure fluid supplied to and held by the holding portion is prevented from entering, and even when it enters the holding portion, it is reliably discharged to the outside by the pressure fluid. As a result, the malfunction of the fluid pressure cylinder, which is a concern when dust enters the inside of the cylinder body, is reliably avoided, so that the piston and the piston rod can always be smoothly displaced, and the fluid pressure cylinder It becomes possible to improve the durability.

  In addition, for example, when the dust is fine particles such as powder or liquid such as water and solvent that are difficult to remove completely with a scraper or the like in a conventional fluid pressure cylinder, The entry can be surely and easily blocked by a pressure fluid having a high pressure relative to the atmospheric pressure, which is more preferable.

1 is an overall longitudinal sectional view of a fluid pressure cylinder to which a dust removing mechanism according to a first embodiment of the present invention is applied. FIG. 2 is an enlarged cross-sectional view showing the vicinity of a subport in the fluid pressure cylinder of FIG. 1. It is an expanded sectional view which shows the rod packing vicinity of FIG. It is sectional drawing along the IV-IV line of FIG. FIG. 2 is an overall longitudinal sectional view showing a state where a piston is displaced toward a rod cover in the fluid pressure cylinder of FIG. 1. FIG. 6 is an enlarged sectional view showing the vicinity of a subport in the fluid pressure cylinder of FIG. 5. It is a whole longitudinal cross-sectional view of the fluid pressure cylinder to which the dust removal mechanism which concerns on the 2nd Embodiment of this invention was applied. FIG. 8 is an overall longitudinal sectional view showing a state in which the piston is displaced toward the rod cover in the fluid pressure cylinder of FIG. 7. FIG. 8 is an overall longitudinal sectional view showing a modified example in which a lubricating member is provided in the fluid pressure cylinder of FIG. 7. FIG. 10 is an overall longitudinal sectional view showing a modified example in which a dust absorbing member is provided in the fluid pressure cylinder of FIG. 9. FIG. 10 is an overall longitudinal sectional view showing a modified example in which a rod cover is provided with a discharge port capable of discharging dust to the outside with respect to the fluid pressure cylinder of FIG. 9. FIG. 10 is a modified example when a rod packing having a pressure reducing mechanism is provided for the fluid pressure cylinder of FIG. 9. FIG. 13 is a partially omitted front view of the rod packing of FIG. 12. 14A is an enlarged sectional view showing the vicinity of the rod packing in FIG. 12, and FIG. 14B is an enlarged sectional view showing a state in which a pressure fluid is supplied to the rod packing in FIG. 14A.

  A preferred embodiment of a dust removing mechanism for a fluid pressure cylinder according to the present invention will be described in detail below with reference to the accompanying drawings.

  In FIG. 1, reference numeral 10 indicates a fluid pressure cylinder to which the dust removing mechanism according to the first embodiment of the present invention is applied.

  1 to 6, the fluid pressure cylinder 10 includes a bottomed cylindrical cylinder tube (cylinder main body) 12, a rod cover 14 attached to one end of the cylinder tube 12, and the cylinder A piston 16 provided inside the tube 12 so as to be displaceable, a piston rod 18 connected to the piston 16 and supported so as to be displaceable by the rod cover 14, and dust S adhering to the piston rod 18 (see FIG. 6). ) Can be removed, and a dust removal mechanism (dust entry preventing means) 20 is included.

  The cylinder tube 12 has a cylinder hole 22 penetrating along the axial direction (arrows A and B directions) at the center thereof, and the cylinder hole 22 is on one end side (arrow A direction) of the cylinder tube 12. It is open. On the other hand, a wall 24 is integrally formed at the other end of the cylinder tube 12 to close the cylinder hole 22.

  Further, a first port 26 for supplying and discharging pressure fluid is formed on the outer surface of one end of the cylinder tube 12, and the supply and discharge of pressure fluid is similarly performed on the outer surface of the other end. A second port 28 is formed. The first and second ports 26 and 28 are connected to a pressure fluid source (not shown) via, for example, a pipe and a switching device (not shown). The first and second ports 26 and 28 communicate with the cylinder hole 22 via the first and second communication passages 30 and 32, respectively.

  The rod cover 14 has a convex portion 34 formed at one end portion thereof and protruding along the axial direction, and is inserted into the cylinder hole 22 of the cylinder tube 12 and fixed. Further, an O-ring 36 is mounted on the outer peripheral surface of the convex portion 34 via an annular groove, and is sandwiched between the inner peripheral surface of the cylinder hole 22 so that the cylinder hole 22 and the rod cover 14 are connected. Prevents leakage of pressure fluid through the gap.

  Further, a rod hole (hole) 38 penetrating along the axial direction is formed in the center portion of the rod cover 14, and the piston rod 18 is inserted into the rod hole 38 so as to be displaceable. A ring-shaped rod packing 42 is attached to an annular groove 40 provided on the inner peripheral surface of the rod hole 38 and extending along the circumferential direction.

  Further, a pressure fluid is supplied from a pressure fluid supply source (not shown) on the outer surface of the rod cover 14 to form a subport (supply port) 44 (described later) constituting the dust removing mechanism 20.

  The piston 16 is formed in a circular cross section, and a piston packing 46 is mounted on the outer peripheral surface of the piston 16 via an annular groove. The piston packing 46 is in sliding contact with the inner peripheral surface of the cylinder hole 22, whereby the cylinder hole 22. Leakage of pressure fluid through between the piston 16 and the piston 16 is prevented.

  In addition, one end portion of the piston rod 18 is inserted into a central portion of the piston 16 through a hole extending along the axial direction (directions of arrows A and B) and crimped. The piston rod 18 is connected so as not to protrude from the end of the piston 16.

  The dust removing mechanism 20 is formed in the rod cover 14 and is connected to the subport 44 to which the pressure fluid is supplied, the annular groove 40 that communicates with the subport 44 and faces the piston rod 18, and the annular rod provided in the annular groove 40. A packing 42.

  The subport 44 opens on the outer surface of the rod cover 14 and extends at a predetermined depth toward the rod hole 38 so as to be orthogonal to the axis of the rod cover 14. The subport 44 communicates with the annular groove 40 via the communication path 48. The sub port 44 is always supplied with a constant pressure fluid from a pressure fluid source (not shown).

  The rod packing 42 is formed of, for example, an elastic material such as rubber or a resin material, and has a main body portion 50 having a substantially rectangular cross section, and protrudes from one side surface of the main body portion 50 sideward to the outer periphery of the piston rod 18. A lip portion 52 that contacts the surface, a yoke 54 that protrudes in a U-shaped cross section from the other side surface of the main body portion 50, and first to first surfaces provided on the inner peripheral surface, one side surface, and the outer peripheral surface of the main body portion 50, respectively. 3 seal portions 56, 58, 60 and a plurality of passages (communication passages) 64 penetrating the main body portion 50 in the radial direction.

  The lip portion 52 is provided on one side surface of the main body portion 50 that is the other end portion side (arrow A direction) of the rod cover 14, and gradually inclines downward, and its tip end portion is on the outer peripheral surface of the piston rod 18. In addition to being in contact with each other, it is provided so as to be able to bend in the radial direction of the rod packing 42 with the connection portion with the main body 50 as a fulcrum.

  In other words, the lip portion 52 is formed so that the tip portion thereof abuts on the outer peripheral surface of the piston rod 18 under the elastic action.

  The yoke 54 protrudes laterally on the other side surface of the main body 50 which is the other end side (arrow A direction) of the rod cover 14 and is provided at a predetermined interval on the outer peripheral surface side and the inner peripheral surface side. It is done. One yoke 54 provided on the outer peripheral side contacts the bottom surface of the annular groove 40, and the other yoke 54 provided on the inner peripheral side contacts the outer peripheral surface of the piston rod 18.

  Further, the recessed portion 62 provided between the yokes 54 is formed so that the pressure fluid pushed out from the cylinder hole 22 side is spread and is prevented from leaking to the outside through the annular groove 40. To do.

  The first to third seal portions 56, 58, 60 are formed to protrude at a predetermined height with respect to the inner peripheral surface, one side surface, and the outer peripheral surface of the main body portion 50, and are formed on the inner peripheral surface. Similar to the lip portion 52, the one seal portion 56 abuts on the outer peripheral surface of the piston rod 18 and is provided at a predetermined interval from the lip portion 52. In this way, the first seal portion 56 abuts on the outer peripheral surface of the piston rod 18, thereby preventing the pressure fluid from leaking outside between the rod hole 38 and the outer peripheral surface of the piston rod 18. .

  Further, the second seal portion 58 formed on one side surface of the main body portion 50 abuts on the side surface of the annular groove 40, and a set of third seal portions 60 formed on the outer peripheral surface is formed on the bottom surface of the annular groove 40. Abut.

  That is, in the main body portion 50 constituting the rod packing 42, the lip portion 52 and the first seal portion 56 are in contact with the outer peripheral surface of the piston rod 18, the second seal portion 58 is in contact with the side surface of the annular groove 40, and Since the third seal portion 60 is in contact with the bottom surface of the annular groove 40, the main body portion 50 is provided at a predetermined distance from each other without contacting the piston rod 18 and the annular groove 40. Yes.

  As shown in FIG. 4, a plurality of (for example, four) passages 64 are provided at regular intervals along the circumferential direction of the main body portion 50, and are provided between the outer peripheral surface and the inner peripheral surface of the main body portion 50. And the passage 64 opens at a position between the pair of third seal portions 60 on the outer peripheral surface, while the lip portion 52 and the first seal portion 56 are formed on the inner peripheral surface. It is opened at a position between.

  The passage 64 is formed at a position that is in line with the communication passage 48 and the subport 44 when the rod packing 42 is mounted in the annular groove 40. That is, by providing the third seal portion 60 on both sides of the passage 64, the pressure fluid supplied from the subport 44 to the passage 64 is prevented from leaking from between the rod packing 42 and the annular groove 40. To do.

  A space portion (holding portion) 66 surrounded by the lip portion 52 and the first seal portion 56 and communicating with the passage 64 is provided on the inner peripheral side of the main body portion 50.

  The fluid pressure cylinder 10 to which the dust removing mechanism 20 according to the first embodiment of the present invention is applied is basically configured as described above. Next, its operation and effects will be described. . The state where the piston 16 shown in FIG. 1 is displaced toward the wall portion 24 side (arrow B direction) of the cylinder tube 12 will be described as an initial position.

  First, by introducing the pressure fluid from the pressure fluid supply source (not shown) into the second port 28 at this initial position, the pressure fluid is supplied to the cylinder hole 22 through the second communication passage 32, and the pressure fluid The piston 16 is displaced toward the rod cover 14 (in the direction of arrow A) under the pressing action of. Accordingly, the piston rod 18 is displaced so as to gradually protrude from the other end of the rod cover 14 to the outside.

  At this time, simultaneously, a pressure fluid is supplied from a pressure fluid supply source (not shown) to the subport 44, introduced into the annular groove 40 through the communication passage 48, and then supplied to the space 66 through the passage 64 of the rod packing 42. The The space 66 is maintained in a state of being pressurized to a predetermined pressure because the pressure fluid is not supplied and led out to the outside.

  In other words, the space 66 is always maintained at a constant pressure that is higher than the atmospheric pressure.

  Then, the piston 16 is further displaced toward the rod cover 14 (in the direction of arrow A), and the piston 16 abuts against one end of the rod cover 14, whereby the displacement is stopped as shown in FIG. This is the displacement end position.

  Next, when the piston 16 is returned from the displacement end position shown in FIG. 5 to the initial position again, the pressure fluid supplied to the second port 28 is supplied to the first port via a switching device (not shown). By being supplied to 26, the piston 16 is gradually pressed in the direction away from the rod cover 14 (direction of arrow B) by the pressure fluid supplied to the cylinder hole 22. In this case, the second port 28 is open to the atmosphere.

  As the piston 16 is displaced, the piston rod 18 is gradually displaced so as to be pulled into the rod cover 14 and the cylinder tube 12. At this time, dust or the like (for example, powder) in the atmosphere adheres to the outer peripheral surface of the piston rod 18 exposed to the outside, but the lip portion of the rod packing 42 is accompanied by the displacement of the piston rod 18. Part of the dust that has been removed by the nozzle 52 and that has not been removed moves into the lip portion 52 side (in the direction of arrow A) by the pressure fluid filled in the space 66 when entering the inside of the lip portion 52. Pushed out. That is, for example, dust such as powder is removed by the lip portion 52 of the rod packing 42, and the lip portion 52 is separated from the piston rod 18 by dust accumulated on the end portion of the lip portion 52. When pushed open, the pressure fluid filled in the space 66 is led out and blown off to prevent further entry.

  Finally, the pressure fluid is continuously supplied from the subport 44 to the space portion 66 of the rod packing 42 while the piston 16 continues to be displaced toward the wall 24 side (arrow B direction). Therefore, the dust that has entered the space 66 is reliably and preferably excluded to the outside, and does not enter the cylinder tube 12 (in the direction of arrow B). Then, as shown in FIG. 1, when the piston 16 abuts against the wall portion 24, the supply of the pressure fluid from the first port 26 is stopped and the initial position is obtained.

  As described above, in the first embodiment, the rod cover 14 is provided with the sub port 44 to which pressure fluid is constantly supplied, and the pressure fluid supplied to the sub port 44 is provided in the space 66 provided in the rod packing 42. Has been introduced. With this configuration, when the piston rod 18 is displaced so as to be drawn into the rod cover 14, dust adhering to the outer peripheral surface of the piston rod 18 is prevented from entering the space 66. In addition, when the dust accumulates in the lip portion 52, the lip portion 52 is pushed and opened in a direction away from the piston rod 18 by the accumulated dust, and is supplied into the space portion 66. It can be reliably discharged to the outside by being blown off by the pressurized fluid.

  As a result, the dust adhering to the outer peripheral surface of the piston rod 18 is reliably prevented from entering the cylinder tube 12 through the rod cover 14, and the fluid pressure cylinder 10 is a concern when the dust enters. Since malfunctions can be reliably avoided, the piston 16 and the piston rod 18 can always be displaced smoothly, and the durability can be improved.

  In addition, for example, even when the dust is fine particles such as powder that is difficult to remove completely with a conventional scraper or the like, or liquid such as water or a solvent, the space is maintained at a high pressure with respect to atmospheric pressure. Since the structure prevents the dust from entering due to a pressure difference between 66 and the atmospheric pressure, the dust can be more reliably prevented from entering.

  Next, a fluid pressure cylinder 100 to which the dust removing mechanism 102 according to the second embodiment is applied is shown in FIGS. The same components as those of the fluid pressure cylinder 10 to which the dust removing mechanism 20 according to the first embodiment described above is applied are denoted by the same reference numerals, and detailed description thereof is omitted.

  The dust removing mechanism 102 according to the second embodiment is provided with a switching mechanism 104 that can switch the supply state of the pressure fluid supplied to the rod packing 42, and therefore the dust according to the first embodiment. This is different from the removal mechanism 20.

  The dust removing mechanism 102 includes a first bypass passage 106 that communicates with the first port 26, a second bypass passage 108 that communicates with the second port 28, and the first bypass passage 106 and the second bypass passage 108. A valve chamber 110 provided between them, a switching valve (switching valve) 112 which is provided so as to be displaceable along the axial direction of the valve chamber 110 and constitutes a switching mechanism 104, and mounting of the valve chamber 110 and the rod packing 42 And a lead-out passage 114 connecting the annular groove 40 formed.

  The first bypass passage 106 is connected to the side of the first port 26 and extends toward the rod cover 14 (in the direction of arrow A), and the second bypass passage 108 is connected to the second port 28. It extends from the middle of the two communicating passages 32 toward the rod cover 14 side (in the direction of arrow A). The second bypass passage 108 is formed so as not to communicate with the first communication passage 30 connected to the first port 26.

  The valve chamber 110 is formed in the rod cover 14 and has a predetermined length along the axial direction. A first end connected to the first bypass passage 106 is connected to the cylinder body side (arrow B direction) at one end. The connection passage 116 is connected, and a second connection passage 118 connected to the second bypass passage 108 is connected to the other end.

  In addition, a lead-out passage 114 is connected to a lower portion of the valve chamber 110 at a position that is a substantially central portion along the axial direction, and extends toward the inner peripheral side of the rod cover 14. The lead-out passage 114 is formed so as not to communicate with the second connection passage 118.

  On the other hand, a switching valve 112 that freely displaces between one end and the other end is provided inside the valve chamber 110, and when pressure fluid is supplied to the valve chamber 110 through the first connection passage 116. Is pressed by the pressure fluid and displaced to the other end side (second connection passage 118 side), and conversely, when pressure fluid is supplied to the valve chamber 110 through the second connection passage 118, Then, it is pressed by the pressure fluid and displaced to one end side (first connection passage 116 side). Thereby, the 2nd connection passage 118 or the 1st connection passage 116 is obstruct | occluded, and the communication with the valve chamber 110 will be interrupted | blocked.

  In the fluid pressure cylinder 100 provided with the dust removing mechanism 102 described above, at the initial position shown in FIG. 7, the pressure fluid is introduced from the pressure fluid supply source (not shown) into the second port 28 at this initial position. Accordingly, the pressure fluid is supplied to the cylinder hole 22 through the second communication passage 32, and the piston 16 is displaced toward the rod cover 14 (in the direction of arrow A) under the pressing action of the pressure fluid. The rod 18 is displaced so as to gradually protrude outward from the other end of the rod cover 14. In this case, the first port 26 is open to the atmosphere.

  At the same time, a part of the pressure fluid is supplied from the second port 28 to the valve chamber 110 through the second bypass passage 108 and the second connection passage 118, and the switching valve 112 is moved to one end side (arrow) along the axial direction. (B direction) is pressed and displaced. As a result, the second connection passage 118 and the outlet passage 114 communicate with each other via the valve chamber 110, and therefore, the pressure fluid flows to the rod packing 42 side through the outlet passage 114 and is introduced into the space 66 through the passage 64. To go.

  Then, when the piston 16 is further displaced toward the rod cover 14 and the piston 16 comes into contact with one end portion of the rod cover 14, the displacement end position is reached where the displacement is stopped.

  Next, when the piston 16 is returned from the displacement end position shown in FIG. 8 to the initial position again, the pressure fluid supplied to the second port 28 is supplied to the first port 26 via a switching device (not shown). 7, as shown in FIG. 7, the pressure fluid supplied to the cylinder hole 22 gradually pushes the piston 16 in the direction away from the rod cover 14 (arrow B direction). Accordingly, the piston rod 18 is gradually displaced so as to be gradually drawn into the rod cover 14. In this case, the second port 28 is open to the atmosphere.

  At the same time, a part of the pressure fluid supplied to the first port 26 is supplied from the first port 26 to the valve chamber 110 through the first bypass passage 106 and the first connection passage 116, and the switching valve 112 is connected to the axis line. It is pushed and displaced along the direction toward the other end side, that is, the second connection passage 118 side (arrow A direction). As a result, the first connection passage 116 and the outlet passage 114 communicate with each other through the valve chamber 110, so that the pressure fluid flows to the rod packing 42 side through the outlet passage 114 and is introduced into the space 66 through the passage 64. The

  In this way, when the piston rod 18 is gradually displaced into the rod cover 14 and the cylinder tube 12, dust or the like in the atmosphere is exposed on the outer peripheral surface of the piston rod 18 exposed to the outside. Although adhering, it is removed by the lip portion 52 of the rod packing 42 in accordance with the displacement of the piston rod 18, and part of the dust remaining without being removed enters the space inside the lip portion 52. The pressure fluid filled in the portion 66 is pushed out toward the lip portion 52 side. That is, dust such as powder is removed by the lip portion 52 of the rod packing 42, and the lip portion 52 is pushed away in a direction away from the piston rod 18 by dust accumulated on the end portion of the lip portion 52. When this occurs, the pressurized fluid filled in the space 66 is led out and blown away, preventing further entry.

  Since the pressure fluid is continuously supplied from the first port 26 to the space portion 66 of the rod packing 42 even while the piston 16 continues to be displaced toward the wall portion 24 side, Dust or the like is prevented from entering the space 66, and the dust that has entered the space 66 is reliably and preferably excluded to the outside and does not enter the cylinder tube 12 side. Then, as shown in FIG. 7, when the piston 16 comes into contact with the wall portion 24, the supply of the pressure fluid from the first port 26 is stopped and the initial position is obtained.

  As described above, in the second embodiment, a part of the pressure fluid supplied to the first and second ports 26 and 28 is supplied to the rod packing 42 side under the switching action of the switching valve 112. The rod packing 42 is introduced into the space 66. With this configuration, when the piston rod 18 is displaced so as to be pulled into the rod cover 14, dust attached to the outer peripheral surface of the piston rod 18 is prevented from entering the space 66. In addition, when the dust enters the space portion 66, it can be reliably discharged to the outside by the pressure fluid supplied into the space portion 66.

  As a result, the dust adhering to the outer peripheral surface of the piston rod 18 is reliably prevented from entering the cylinder tube 12 through the rod cover 14, and the fluid pressure cylinder 100 is a concern when the dust enters. Since malfunctions can be reliably avoided, the piston 16 and the piston rod 18 can always be displaced smoothly, and the durability can be improved.

  Further, in the above-described configuration, since dust or the like can be removed using a part of the pressure fluid supplied to the first and second ports 26 and 28 for displacing the piston 16, the dust is removed. Therefore, it is not necessary to prepare another port, a pressure fluid source, a pipe, and the like for removing the above, and the equipment can be simplified, and accordingly, the cost can be reduced.

  Furthermore, for example, even when the dust is fine particles such as powder that is difficult to remove completely with a conventional scraper or the like, or a liquid such as water or a solvent, the space is maintained at a high pressure with respect to atmospheric pressure. Since the structure prevents the dust from entering due to a pressure difference between 66 and the atmospheric pressure, the dust can be more reliably prevented from entering.

  Further, as in the fluid pressure cylinder 120 shown in FIG. 9, a lubricating member 122 containing a lubricant may be provided in the rod hole 38 of the rod cover 14 via an annular groove. The lubricating member 122 is a member in which fibers are woven, and is provided on the cylinder tube 12 side with respect to the annular groove 40 in which the rod packing 42 is mounted. And it lubricates suitably by slidingly contacting the outer peripheral surface of the piston rod 18.

  Therefore, by providing the lubricating member 122 between the rod packing 42 and the cylinder tube 12, the lubricity of the piston rod 18 lost due to dust such as powder can be maintained, for example.

  Furthermore, as in the fluid pressure cylinder 130 shown in FIG. 10, a lubricant holding member 132 a and a dust absorbing member 132 b may be provided in the rod hole 38 of the rod cover 14 so as to sandwich the rod packing 42. With such a configuration, dust adhering to the outer peripheral surface of the piston rod 18 is captured by the dust absorbing member 132b and collected in the lip portion 52 of the rod packing 42, and the lip portion 52 is separated from the piston rod 18. The dust blown away by the pressure fluid filled in the space 66 by being pushed open in the separating direction is reliably secured by the dust absorbing member 132b. Therefore, dust is reliably avoided from being discharged to the outside of the fluid pressure cylinder 130 through the rod hole 38, which is suitable when the fluid pressure cylinder 130 is used in a clean room or the like, for example.

  Furthermore, as in the fluid pressure cylinder 140 shown in FIG. 10, a discharge port 142 is provided at a position between the lubrication holding member 132a and the dust absorbing member 132b in the fluid pressure cylinder 130 described above. Also good. The discharge port 142 opens on the outer surface of the rod cover 14 opposite to the side on which the lead-out passage 114 is formed, and penetrates from the outer surface to the rod hole 38.

  Thus, by providing the discharge port 142 communicating with the rod hole 38 and extending to the outside of the rod cover 14, the piston rod 18 is displaced so as to be accommodated inside the rod cover 14, and the piston rod The dust adhering to the outer peripheral surface 18 can be discharged outside the rod cover 14 through the discharge port 142 without entering the inside of the rod packing 42. Therefore, it is preferable that dust is prevented from accumulating inside the rod hole 38.

  Further, for example, by connecting a pipe (not shown) to the discharge port 142, when the fluid pressure cylinder 140 is used in a clean room or the like, it is preferable that dust can be prevented from being discharged into the room.

  On the other hand, the rod packing 152 constituting the fluid pressure cylinder 150 shown in FIGS. 12 to 14 extends in the lateral direction so as to be orthogonal to the first passage 154 opened upward. A second passage 156 that is present, a third passage 158 that is connected to the second passage 156 and bends downward at a substantially central portion of the rod packing 152, and the first passage 154 and the second passage 156. And a ball 160 which is movably provided at a connection site with the two passages 156. Note that the first passage 154 communicates with the outlet passage 114.

  The ball 160 is formed of, for example, a resin material, and is provided so that a part of the ball 160 is inserted into the inner wall surface 162 of the second passage 156, and is disposed at a position that is in line with the first passage 154. The Further, since the ball 160 is urged upward by the elastic force from the inner wall surface 162, the ball 160 is pressed upward by the elastic force and comes into contact with the opening of the first passage 154. The communication between the first passage 154 and the second passage 156 is blocked.

  Further, the rod packing 152 is provided with a recess 164 between the second passage 156 and the lip portion 52, and the recess 164 includes a plurality of ribs spaced at equal intervals along the circumferential direction of the rod packing 152. 166 is provided. The rib 166 is formed so as to connect the inner wall surface 162 of the second passage 156 and the lip 52 in the space 66.

  In the fluid pressure cylinder 150 including the rod packing 152 described above, when no pressure fluid is supplied from the outlet passage 114 to the first passage 154, the ball 160 is moved to the first passage 154 as shown in FIG. 14A. The communication state between the first passage 154 and the second passage 156 is cut off by contacting the opening of the first passage 154, and the pressure fluid is supplied to the lead-out passage 114, and the pressure increases. As shown in FIG. 14B, the ball 160 is pressed downward against the elastic force, and the inner wall surface 162 of the second passage 156 is deformed downward across the recess 164, whereby the first passage The communication cut-off state between 154 and the second passage 156 is released. As a result, the pressure fluid supplied to the first passage 154 is supplied to the space 66 through the second passage 156 and the third passage 158. At this time, the pressing force on the ball 160 has a magnitude obtained by multiplying the pressure P1 of the pressurized fluid supplied from the first passage 154 by the cross-sectional area of the first passage 154.

  Then, when the pressure P1 of the pressurized fluid supplied to the first passage 154 decreases, the elastic force F (see FIG. 14B) urged from the inner wall surface 162 of the second passage 156 and the second passage 156. The pressure P2 (see FIG. 14B) of the introduced pressure fluid overcomes the pressure P1 of the pressure fluid, and the ball 160 is pushed upward, and the ball 160 causes the first passage 154 and the second passage 156 to The gap between is gradually reduced. As a result, the flow rate of the pressure fluid flowing from the first passage 154 to the third passage 158 and the space 66 through the second passage 156 decreases.

  In this way, by providing the pressure reducing mechanism 168 capable of adjusting the pressure of the pressure fluid supplied to the space portion 66 in accordance with the pressure of the pressure fluid supplied to the inside of the rod packing 152, the first or second The pressure fluid supplied to the port to displace the piston can be depressurized and supplied to the space 66 of the rod packing 152. As a result, it is preferable that the pressure of the pressure fluid supplied to the cylinder hole 22 and the pressure fluid supplied to the space 66 of the rod packing 152 can be set separately.

  In the rod packing 152, the pressure of the pressure fluid supplied to the space 66 is freely adjusted by freely changing the shape of the ball 160, the shape of the rib 166, the cross-sectional area of the first passage 154, and the like. be able to.

  The dust removal mechanism of the fluid pressure cylinder according to the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted without departing from the gist of the present invention.

10, 100, 120, 130, 140, 150 ... Fluid pressure cylinder 12 ... Cylinder tube 14 ... Rod cover 16 ... Piston 18 ... Piston rod 20, 102 ... Dust removal mechanism 22 ... Cylinder hole 26 ... First port 28 ... Second Port 38 ... Rod hole 40 ... Annular groove 42, 152 ... Rod packing 44 ... Sub port 50 ... Main body 52 ... Lip part 64 ... Passage 66 ... Space part 104 ... Switching mechanism 106 ... First bypass passage 108 ... Second bypass passage 110 ... Valve chamber 112 ... Switching valve 114 ... Derivation passage 122 ... Lubrication member 132a ... Lubrication holding member 132b ... Dust absorbing member 142 ... Discharge port 160 ... Ball 168 ... Pressure reducing mechanism

Claims (10)

A cylinder body having a pair of ports to which pressure fluid is supplied and a cylinder chamber into which the pressure fluid is introduced from the ports;
A piston provided inside the cylinder chamber so as to be displaceable along the axial direction;
Supported by the cylinder body, a piston rod which is displaced to be coupled to the piston rod protrudes to the outside of the cylinder body,
A rod cover provided at an end of the cylinder body and supporting the piston rod so as to be displaceable along an axial direction;
Provided in the rod cover, and a rod packing having a lip portion extending aforementioned sliding contact with the outer peripheral surface of the piston rod, in a direction away from the piston,
Dust entry preventing means for supplying the pressure fluid toward the piston rod and preventing dust adhering to the piston rod from entering the cylinder body;
With
The dust intrusion preventing means includes a holding portion provided et been pre Symbol pressure fluid is supplied and held between the rod packing and the piston rod, the pressure of a constant pressure in the holding portion provided in the rod cover when possess a supply port for supplying the fluid, and a communication passage for communicating the holding portion and said supply port, displaced in a direction in which the piston rod is retracted into the rod cover side, the outer peripheral surface by the lip portion The dust removing mechanism of the fluid pressure cylinder is characterized in that when the lip portion is separated from the outer peripheral surface by the dust, the pressure fluid of the holding portion is pushed out and blows off the dust. . In the dust removal mechanism according to claim 1,
The dust removal mechanism for a fluid pressure cylinder, wherein the supply port includes a switching mechanism that selectively supplies pressure fluid supplied to one of the pair of ports to the holding unit. In the dust removal mechanism according to claim 2 ,
The switching mechanism is provided at a rod cover that is provided at an end of the cylinder body and supports the piston rod so as to be displaceable along an axial direction. The switching valve is displaced under the action of supplying the pressure fluid; A dust removing mechanism for a fluid pressure cylinder, comprising: a communication passage that communicates either one of the ports and the holding portion with a displacement action of a valve. In the dust removal mechanism according to any one of claims 1 to 3 ,
The dust removal mechanism for a fluid pressure cylinder, wherein the communication passage penetrates from the outer peripheral surface of the rod packing toward the inner peripheral surface and communicates with the holding portion provided to face the inner peripheral surface. . In the dust removal mechanism according to claim 4 ,
A dust removing mechanism for a fluid pressure cylinder, wherein a plurality of the communication passages are provided along a circumferential direction of the rod packing formed in an annular shape. In the dust removal mechanism according to any one of claims 1 to 5 ,
The holding portion is a space that is formed on an inner peripheral surface of the rod packing and that is surrounded by a seal portion that contacts the outer peripheral surface of the piston rod, and the outer peripheral surface of the lip portion and the piston rod. Dust removal mechanism of fluid pressure cylinder. In the dust removal mechanism according to any one of claims 1, 3 to 6,
The rod cover has a hole portion through which the piston rod is inserted, and the hole portion is provided with a dust capturing member capable of capturing and holding the dust. Removal mechanism. According to claim 1, 3-7 dust removing mechanism according to any one of,
The rod cover has a hole through which the piston rod is inserted, and the hole is provided with a lubrication holding member that lubricates the piston rod. . The dust removing mechanism according to claim 7 or 8 ,
A dust removing mechanism for a fluid pressure cylinder, wherein the rod cover is provided with a discharge port that allows the hole to communicate with the outside and discharge the dust to the outside. The dust removing mechanism according to claim 7 or 8 ,
A dust removing mechanism for a fluid pressure cylinder, wherein the rod packing is provided with a pressure reducing mechanism capable of reducing the pressure of the pressure fluid flowing to the piston rod side.

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