JP5397407B2 - Wear ring used in linear actuator - Google Patents

Description

  The present invention relates to a wear ring that is used in a linear actuator including a displacement body that is displaced along an axial direction and is attached to the displacement body.

  2. Description of the Related Art Conventionally, for example, a fluid pressure cylinder including a piston that is linearly displaced by a pressure fluid is known as a driving means for conveying and positioning a workpiece or driving various industrial machines. In the fluid pressure cylinder, a piston is inserted into a cylindrical cylinder tube so as to be displaceable, and a piston rod connected to the piston is supported by a rod cover so as to be displaceable. Then, when the pressure fluid is introduced into the cylinder tube from the ports provided in the cylinder tube and the rod cover, the piston and the piston rod are displaced along the axial direction. In such a fluid pressure cylinder, a packing and a wear ring are mounted on the outer peripheral surface of the piston, and are in sliding contact with the inner peripheral surface of the cylinder tube (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 5-187413

  In the fluid pressure cylinder as described above, the piston is generally arranged coaxially with the cylinder tube, and the packing and wear ring provided on the outer peripheral surface thereof are uniform with respect to the inner peripheral surface of the cylinder tube. It is comprised so that it may slidably contact. However, for example, when a load is applied to the end of the piston rod protruding from the cylinder tube in a direction orthogonal to the axis thereof, or the piston rod and the piston rod are slightly moved in the cylinder tube due to its own weight. When it is inclined only, the packing and the wear ring are on one side with respect to the inner peripheral surface of the cylinder tube. This increases the sliding resistance when the piston is displaced, resulting in a displacement resistance of the piston and a problem that the wear ring is unevenly worn.

  The present invention has been made in consideration of the above-described problems, and is a wear ring used in a linear actuator that can smoothly linearly displace the displacement body even when the displacement body is inclined with respect to the body. The purpose is to provide.

In order to achieve the above object, the present invention provides a linear actuator having a body and a displacement body provided so as to be displaceable along the inside of the body, and is mounted on the outer peripheral surface of the displacement body via a groove. An annular wear ring that contacts the inner wall surface of the body,
The wear ring is formed in an annular shape, and has a main body portion having an outer peripheral surface having a planar cross-section that contacts the inner wall surface;
A bulging portion that is provided on the inner peripheral surface of the main body portion, is formed in a cross-sectional shape that bulges in a radially inward direction, and comes into contact with the bottom wall of the groove portion;
With
When the displacement body is tilted with respect to the axis of the body, the main body is tilted in the groove while maintaining the outer peripheral surface in contact with the inner wall surface.

  According to the present invention, in the wear ring that is mounted on the outer peripheral surface of the displacement body via the groove portion, the annular main body portion having an outer peripheral surface having a planar cross section that comes into contact with the inner wall surface of the body, and the main body portion And a bulging portion having a cross-sectional shape that bulges inward in the radial direction, and is mounted so that the bulging portion contacts the bottom wall of the groove portion. When the displacement body is inclined with respect to the axis of the body, the wear ring is tilted in the groove portion in order to maintain the outer peripheral surface of the wear ring in contact with the inner wall surface of the body.

  Therefore, in the linear actuator, even if the displacement body is inclined with respect to the axis of the body for some reason, the wear ring is tilted through the bulging portion, whereby the outer peripheral surface of the main body portion and the inner wall surface of the body are The contact area does not change, and the contact area can always be constant. As a result, even when the displacement body is inclined, an increase in the surface pressure applied to the wear ring can be suppressed, so that the sliding resistance when the displacement body is displaced along the inside of the body is increased. The wearering can smoothly and stably displace the displacement body along the body.

  Moreover, it is good to form a bulging part by bulging in cross-sectional arc shape.

  Further, the main body may be filled with a lubricant, and a lubricating groove for supplying the lubricant may be provided between the body and the displacement body.

  Furthermore, a lubricating groove may be formed on the outer peripheral surface of the main body.

  Also, a plurality of lubricating grooves may be provided and spaced apart from each other and arranged in parallel.

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

  That is, in the linear actuator, even when the displacement body is inclined with respect to the axis of the body for some reason, the wear ring tilts through the bulging portion, so that the outer peripheral surface of the main body portion and the inner wall surface of the body Since the contact area does not change and can always be a constant contact area, it is possible to avoid an increase in sliding resistance when the displacement body is displaced along the inside of the body. Thus, the displacement body can be displaced smoothly and stably along the body.

1 is an overall cross-sectional view of a fluid pressure cylinder in which a wear ring according to a first embodiment of the present invention is used. It is an expanded sectional view which shows the wear ring vicinity in the fluid pressure cylinder of FIG. It is a front view of the wear ring shown in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 2 is an overall cross-sectional view showing a case where a piston and a piston rod are inclined with respect to an axis of a cylinder tube in the fluid pressure cylinder of FIG. 1. It is an expanded sectional view showing the wear ring neighborhood in the fluid pressure cylinder of FIG. It is an expanded sectional view showing the wear ring neighborhood concerning a 2nd embodiment of the present invention. It is an expanded sectional view which shows the modification in the wear ring of FIG. It is an expanded sectional view which shows another modification in the wear ring of FIG.

  The preferred embodiment of the wear ring used in the linear actuator 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 which is a linear actuator to which a wear ring according to the first embodiment of the present invention is applied.

  As shown in FIGS. 1 and 2, the fluid pressure cylinder 10 includes a cylinder tube (body) 12 formed in a bottomed cylindrical shape, and a rod cover 14 attached to an open end of the cylinder tube 12. And a piston (displacement body) 16 that displaces the inside of the cylinder tube 12 along the axial direction (arrows A and B directions), a piston rod 18 connected to the piston 16, and an outer peripheral surface of the piston 16. And a wear ring 20 to be mounted.

  A first port 22 through which pressure fluid is supplied / discharged is formed on one side of the cylinder tube 12 at its side surface. The first port 22 communicates with a cylinder chamber 26 formed inside the cylinder tube 12 through a communication path 24. The cylinder chamber 26 is formed along the inside of the cylinder tube 12, and the piston 16 is disposed in the cylinder chamber 26 so as to be freely displaceable. The cylinder chamber 26 includes a first cylinder chamber 28 formed between the piston 16 and one end portion where the cylinder tube 12 is closed, and a second cylinder chamber formed between the piston 16 and the rod cover 14. 32. That is, the first cylinder chamber 28 communicates with the first port 22 through the communication path 24.

  The rod cover 14 has a threaded portion formed on the outer peripheral surface of one end thereof, and is integrally connected by being screwed to the opening end of the cylinder tube 12. At this time, the seal member 34 attached to the opening end of the cylinder tube 12 abuts against the end surface of the rod cover 14, so that the airtightness in the cylinder chamber 26 is suitably maintained.

  Further, a second port 36 through which pressure fluid is supplied and discharged is formed on the side surface of the rod cover 14, and the second port 36 has a rod hole 40 penetrating through the central portion of the rod cover 14 through the communication path 38. Communicate. This rod hole 40 penetrates along the axial direction (arrow A, B direction) of the rod cover 14, and the piston rod 18 is inserted through the rod hole 40 so as to be displaceable.

  A bush 42 is attached to the rod hole 40 through an annular groove at a substantially central portion along the axial direction. On the other end side (arrow B direction) of the rod cover 14 adjacent to the bush 42, A rod packing 44 is mounted via an annular groove. The bush 42 is formed, for example, from a metal material into a ring shape having a substantially rectangular cross section, and the inner peripheral surface thereof is in contact with the outer peripheral surface of the piston rod 18. When the piston rod 18 is displaced along the axial direction (arrows A and B directions), the piston rod 18 is supported in a freely displaceable manner by contacting the outer peripheral surface thereof.

  The piston 16 is formed of, for example, a metal material, and is inserted into a piston hole 46 penetrating through a central portion thereof on one end side (in the direction of arrow A) of the piston rod 18 and is connected by being screwed.

  In addition, first to third annular grooves 48, 50, 52 spaced apart from each other by a predetermined distance along the axial direction (arrow A, B direction) of the piston 16 are formed on the outer peripheral surface of the piston 16, and the rod cover 14 side. A piston packing 54 is attached to the first annular groove 48 (in the direction of arrow B), and a magnet 56 is attached to the second annular groove 50 adjacent to the first annular groove 48, which is farthest from the rod cover 14. The wear ring 20 is attached to the third annular groove (groove portion) 52. The first to third annular grooves 48, 50, 52 are all formed in a substantially rectangular cross section.

  In other words, the air tightness of the first and second cylinder chambers 28 and 32 in the cylinder tube 12 is suitably maintained by the piston packing 54, and the magnet 56 is connected via position detecting means (not shown) provided in the cylinder tube 12. By detecting, the position along the axial direction (arrow A, B direction) of the piston 16 can be detected.

  As shown in FIGS. 1 to 4, the wear ring 20 is formed of, for example, a resin material and includes an annular main body 58 that contacts the inner wall surface 12 a of the cylinder tube 12.

  The main body 58 has a cutout portion 60 that is partially cut along the axial direction (arrow A and B directions), and is formed so as to be radially expandable in the radial direction via the cutout portion 60. The cross section is formed in a substantially rectangular shape that is long in the axial direction.

  The outer peripheral surface 58a of the main body portion 58 is formed in a cross-sectional plane substantially parallel to the axis of the main body portion 58, while the inner peripheral surface 58b of the main body portion 58 is gentle with a predetermined radius in the radially inward direction. A chamfered portion 64 inclined in an oblique direction is formed at a boundary portion between the inner peripheral surface 58b and both side walls 62a and 62b. The chamfered portion 64 is formed at an angle of 45 ° with respect to the side walls 62a and 62b, for example. That is, the wear ring 20 is held in a state in which the inner peripheral surface 58 b formed in an arcuate cross section is in line contact with the bottom wall surface of the third annular groove 52.

  When the wear ring 20 is mounted on the piston 16, the outer peripheral surface 58 a is in surface contact with and contacts the inner wall surface 12 a of the cylinder tube 12, while the inner peripheral surface 58 b is the third annular shape in the cylinder tube 12. It is in contact with the bottom wall surface of the groove 52.

  The piston rod 18 is formed with a thin shaft portion 66 to which the piston 16 is connected on one end side (arrow A direction), and has a diameter larger than that of the thin shaft portion 66 on the other end side (arrow B direction). The thick shaft portion 68 is formed. The thick shaft portion 68 is inserted into the rod hole 40 of the rod cover 14 and is supported via the bush 42 so as to be displaceable along the axial direction (the directions of arrows A and B). Further, the rod packing 44 comes into contact with the outer peripheral surface 58a of the thick shaft portion 68, and leakage of the pressure fluid from between the rod hole 40 and the piston rod 18 is prevented.

  The fluid pressure cylinder 10 that is a linear actuator using the wear ring 20 according to the first embodiment of the present invention is basically configured as described above. The effect will be described.

  By supplying a pressure fluid (for example, compressed air) from a pressure fluid supply source (not shown) to the first port 22, the pressure fluid supplied to the first port 22 is introduced into the first cylinder chamber 28 through the communication path 24. Is done. Thereby, the piston 16 provided in the cylinder tube 12 is pressed from the initial position shown in FIG. 1 toward the rod cover 14 (arrow B direction), and the piston 16 moves toward the rod cover 14. Displace. The pressure fluid in the second cylinder chamber 32 is discharged to the outside from the second port 36 in a state where no pressure fluid is supplied through the communication passage 38.

  At this time, the wear ring 20 is displaced while its outer peripheral surface 58 a is in sliding contact with the inner wall surface 12 a of the cylinder chamber 26.

  Then, the piston 16 comes into contact with the end surface of the rod cover 14 to be the displacement end position of the piston 16 in the fluid pressure cylinder 10.

  On the other hand, when the piston 16 located at the displacement end position described above is displaced in the direction away from the rod cover 14 (arrow A direction), the pressure fluid supply source (not shown) is supplied to the first port 22. The pressurized fluid is supplied to the second port 36 under the switching action of a switching valve (not shown), and the first port 22 is not supplied with the pressurized fluid.

  The pressure fluid supplied to the second port 36 is introduced into the second cylinder chamber 32 through the communication passage 38, and the piston 16 is pressed in a direction away from the rod cover 14 (arrow A direction), whereby the piston 16 is displaced away from the rod cover 14. In this case as well, the wear ring 20 is displaced while its outer peripheral surface 58a is in sliding contact with the inner wall surface 12a of the cylinder chamber 26, and the inner peripheral surface 58b is in contact with the bottom wall surface of the third annular groove 52. is there. The pressure fluid in the first cylinder chamber 28 is discharged from the first port 22 to the outside through the communication path 24.

  Then, when the piston 16 abuts on the closed one end side (arrow A direction) of the cylinder tube 12, the piston 16 returns to the initial position of the piston 16 in the fluid pressure cylinder 10 (see FIG. 1).

  Next, for example, a load F is applied to the other end portion of the piston rod 18 in a direction orthogonal to the axis of the piston rod 18 (vertical direction), and the piston rod 18 and the piston 16 are directed to the axis of the cylinder tube 12. The case of tilting will be described with reference to FIGS.

  When such a load F (see FIG. 5) is applied, the other end portion of the piston rod 18 is pressed downward, and the other end portion is lowered with a portion supported by the rod cover 14 as a fulcrum. And incline by a predetermined angle. As a result, one end portion of the piston rod 18 and the piston 16 connected to the one end portion are disposed in the cylinder chamber 26 via a clearance provided between the outer peripheral surface 58a of the piston 16 and the inner wall surface 12a of the cylinder chamber 26. In this state, it is inclined upward by a predetermined angle.

  At this time, since the inner peripheral surface 58b of the wear ring 20 has a circular arc shape and bulges in the radially inward direction, the inner peripheral surface 58a remains in surface contact with the inner wall surface 12a of the cylinder tube 12. The wear ring 20 tilts inside the third annular groove 52 using 58b as a fulcrum. That is, the wear ring 20 is tilted by a predetermined angle with respect to the piston 16 so as to maintain a contact state with the inner wall surface 12a of the cylinder tube 12 when the piston 16 is tilted with respect to the axis of the cylinder tube 12. Therefore, the contact area between the inner peripheral surface 58b and the outer peripheral surface 58a of the wear ring 20 does not change.

  In other words, the wear ring 20 is tilted so as to be inclined with respect to the axis line from a state substantially parallel to the axis line of the piston 16, so that the outer peripheral surface 58 a of the wear ring 20 is always in contact with the inner wall surface 12 a of the cylinder tube 12. Can be kept in surface contact with each other.

  As a result, even if a load F is applied to the other end of the piston rod 18 for some reason and the piston 16 is inclined in the cylinder chamber 26, the piston rod 18 and the piston 16 are not aligned with the axis of the cylinder tube 12. Compared with the normal state provided on the same axis (see FIG. 1), the contact area between the wear ring 20 and the cylinder tube 12 can be made constant at all times. In addition, an increase in the surface pressure applied to the wear ring 20 can be suppressed. In other words, the contact area of the wear ring 20 with respect to the cylinder tube 12 does not change, and a stable contact area can be obtained.

  Thereby, in the fluid pressure cylinder 10, it is avoided that the sliding resistance increases when the piston 16 is displaced along the axial direction (arrows A and B directions). It becomes possible to displace the rod 18 smoothly and stably along the axial direction of the cylinder tube 12 (arrows A and B directions).

  Next, a wear ring 100 according to a second embodiment and a fluid pressure cylinder 102 to which the wear ring 100 is applied are shown in FIG. In addition, the same referential mark is attached | subjected to the component same as the fluid pressure cylinder 10 to which this wear ring 20 which concerns on 1st Embodiment mentioned above was applied, and the detailed description is abbreviate | omitted.

  The wear ring 100 according to the second embodiment is the first embodiment in that the outer peripheral surface 104a of the main body 104 has a groove portion (lubricating groove) 106 that can be filled with the lubricant S. This is different from the wear ring 20 according to FIG. The inner peripheral surface 104b of the wear ring 100 is formed in substantially the same shape as the wear ring 20 according to the first embodiment.

  For example, the groove 106 is formed in a rectangular cross section, is formed in an annular shape along the outer peripheral surface 104a of the main body 104, and has a width dimension along the axial direction (arrow A, B direction) of the main body 104. Is provided at a substantially central portion. The cross-sectional shape of the groove 106 is not limited to a rectangular shape. For example, a groove (lubricating groove) 106a is connected to the inner peripheral side of the main body 104 like a wear ring 100a shown in FIG. It is good also as a cross-sectional triangle shape which becomes a taper shape toward. And when the outer peripheral surface 104a of the main-body part 104 contact | abuts to the inner wall surface 12a of the cylinder tube 12, it will be in the state by which the lubricant S was enclosed inside the groove parts 106 and 106a.

  Furthermore, the groove 106 is not limited to a single case with respect to the outer peripheral surface 104a of the main body 104. For example, the width of the main body 104 can be changed like a wear ring 100b shown in FIG. A pair of groove portions (lubricating grooves) 106b may be provided in parallel at positions that are spaced apart from each other by a predetermined distance from the center in the direction and on the side walls 62a and 62b side. In this case, by making the cross-sectional area of the pair of groove portions 106b substantially equal to the cross-sectional area of the single groove portion 106, the filling amount of the lubricant S filled in the groove portions 106b can be made equal. Become.

  In a state where these wear rings 100, 100a, 100b are mounted on the piston 16, the outer peripheral surface 104a comes into surface contact with the inner wall surface 12a of the cylinder tube 12 and comes into contact therewith, so that the grooves 106, 106a, 106b are filled. Since the lubricant between the piston 16 and the cylinder tube 12 is lubricated by the agent S, the piston 16 can be displaced more smoothly along the cylinder tube 12.

  Of course, the wear ring used in the linear actuator according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10, 102 ... Fluid pressure cylinder 12 ... Cylinder tube 14 ... Rod cover 16 ... Piston 18 ... Piston rod 20, 100, 100a, 100b ... Wear ring 26 ... Cylinder chamber 58, 104 ... Main-body part 58a, 104a ... Outer peripheral surface 58b, 104b ... Inner peripheral surfaces 106, 106a, 106b ... Groove portions 62a, 62b ... Side walls 64 ... Chamfered portions

Claims (5)

In a linear actuator having a body and a displacement body that is displaceably provided along the inside of the body, an annular wear ring that is attached to the outer peripheral surface of the displacement body via a groove and contacts the inner wall surface of the body. There,
The wear ring is formed in an annular shape, and has a main body portion having an outer peripheral surface having a planar cross-section that contacts the inner wall surface;
A bulging portion that is provided on the inner peripheral surface of the main body portion, is formed in a cross-sectional shape that bulges in a radially inward direction, and comes into contact with the bottom wall of the groove portion;
With
The main body is tilted in the groove while the outer peripheral surface is in contact with the inner wall when the displacement body is tilted with respect to the axis of the body. Wearing used for The wear ring according to claim 1, wherein
The bulge is a wear ring used in a linear actuator, wherein the bulge is bulged in a circular arc shape. The wear ring according to claim 1 or 2,
A wear ring used in a linear actuator, wherein the main body portion is filled with a lubricant and provided with a lubricating groove for supplying the lubricant between the body and the displacement body. The wear ring according to claim 3,
The wear ring used in the linear actuator, wherein the lubricating groove is formed on an outer peripheral surface of the main body. In the wearing according to claim 3 or 4,
A wear ring used in a linear actuator, wherein a plurality of the grooves for lubrication are provided and are arranged in parallel and spaced apart from each other.

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