JP2017180780A - Fluid pressure cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a fluid pressure cylinder.SOLUTION: A hydraulic cylinder 100 is equipped with a cushion portion 40 which reduces the speed of a piston rod 20 near a stroke end upon the actuation of expansion; and an abutting portion 51 on which the cushion portion 40 abuts near the stroke end upon the actuation of expansion. The cushion portion 40 has a cushion ring 41 which defines a cushion passage 42 applying resistance on passing hydraulic fluid; and a regulating pin 45 which regulates the relative movement of the cushion ring 41 to the piston rod 20 while being stored in an annular groove 25 formed on the outer peripheral surface of the piston rod 20. As the cushion ring 41 and the abutting portion 51 abut on each other near the stroke end upon the actuation of the expansion, the regulating pin 45 gets out of the annular groove 25, and the relative movement of the cushion ring 41 to the piston rod 20 is accepted. The hydraulic fluid of a rod side chamber 1 is discharged from a supply/discharge passage 4 through a cushion passage 42.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fluid pressure cylinder.

  Patent Document 1 discloses a fluid pressure cylinder having a cushion mechanism. The cushion mechanism disclosed in Patent Document 1 includes a rod recess that opens to the outer peripheral surface of the piston rod, a movable sleeve that slidably fits to the outer peripheral surface of the piston rod, and a groove-shaped opening that opens to the inner peripheral surface of the movable sleeve. A slit, and a spring that biases the movable sleeve away from the piston toward the cylinder head.

  In the fluid pressure cylinder of Patent Document 1, the cushion mechanism has a flow of working fluid that has flowed directly from the rod chamber to the supply / discharge port when the movable sleeve comes into contact with the cylinder head in the vicinity of the stroke end during the extension operation. Is switched to the flow of the working fluid flowing out to the supply / discharge port through the slit and the rod recess. Thereby, the piston rod is smoothly decelerated by the resistance applied to the flow of the working fluid passing through the slit, and the cushion function is exhibited.

JP 2012-172893 A

  In the fluid pressure cylinder disclosed in Patent Document 1, the movable sleeve and the piston rod are moved relative to each other in the vicinity of the stroke end during the extension operation to exert a cushion function, and the movable sleeve and the piston rod are moved together during the contraction operation. The movable sleeve is supported by a spring provided in the rod chamber.

  However, if a spring is provided in the rod side chamber as in this fluid pressure cylinder, the entire length becomes longer and the fluid pressure cylinder becomes larger.

  The present invention has been made in view of the above problems, and an object thereof is to reduce the size of a fluid pressure cylinder.

  The first invention is a fluid pressure cylinder, a cylinder tube, a piston rod inserted into the cylinder tube, a piston connected to the tip of the piston rod and dividing the inside of the cylinder tube into a rod side chamber and a bottom side chamber, Provided in the cylinder tube, provided on the outer circumference of the piston rod, which decelerates the piston rod near the stroke end during extension operation, a supply / exhaust passage that communicates with the rod side chamber and through which the working fluid supplied and discharged to the rod side chamber passes. And a contact portion with which the cushion portion abuts near the stroke end during the extension operation, and the cushion portion is disposed on the outer surface of the piston ring and the cushion ring that abuts the contact portion near the stroke end during the extension operation. Regulations that regulate the relative movement of the cushion ring with respect to the piston rod while being accommodated in the formed recess. And the contact between the cushion ring and the contact portion in the vicinity of the stroke end during the extension operation, the direct communication between the supply / exhaust passage and the rod side chamber is blocked by the cushion ring and the restricting portion. Escapes from the recess and allows relative movement of the cushion ring with respect to the piston rod, and the working fluid in the rod side chamber is discharged from the supply / discharge passage through the cushion passage that provides resistance to the passing working fluid.

  In the second invention, the inner peripheral surface of the cylinder tube has a sliding surface on which the piston slides and a large-diameter surface formed with an inner diameter larger than the sliding surface, and the restricting portion is slid Escape from the recess is restricted by contact with the surface, and escape from the recess is allowed by facing the large-diameter surface.

  In the first and second inventions, when the cushion portion comes into contact with the contact portion in the vicinity of the stroke end during the extension operation, direct communication between the supply / discharge passage and the rod side chamber is blocked. When the piston rod further moves in the extending direction from the state where the cushion portion and the contact portion are in contact with each other, the relative movement between the piston rod and the cushion ring that is restricted by the restriction portion is allowed. Therefore, in the vicinity of the stroke end of the extension operation, the working fluid discharged from the rod side chamber is guided to the supply / discharge passage through the cushion passage, and the cushion function for decelerating the piston rod is exhibited. As described above, the relative movement of the cushion ring with respect to the piston rod is restricted by the restricting portion, so that the cushion function can be provided near the stroke end during the extension operation without providing a spring for supporting the cushion ring in the rod side chamber. Is demonstrated.

  According to a third aspect of the present invention, at least one of the restricting portion or the recessed portion pushes the restricting portion radially outward along with the movement of the piston rod in the extending direction from the state where the cushion ring and the contact portion abut. An escape guide portion is formed to escape from.

  According to the third aspect of the present invention, the restricting portion can be surely escaped from the recess as the piston rod moves in the extending direction from the state in which the cushion ring and the contact portion abut.

  According to a fourth aspect of the present invention, the inner peripheral surface of the cylinder tube further includes an inner peripheral stepped portion formed between the sliding surface and the large-diameter surface, and at least one of the restricting portion or the inner peripheral stepped portion includes: In accordance with the movement of the piston rod in the contraction direction from the state in which the cushion ring and the contact portion abut, an accommodation guide portion is formed that pushes the restricting portion radially inward to be accommodated in the recess.

  According to the fourth aspect of the present invention, the piston rod is moved in the contraction direction by reliably accommodating the restricting portion in the recess as the piston rod moves in the contraction direction from the state in which the cushion ring and the contact portion abut. Can be made.

  According to a fifth aspect of the present invention, an axial gap is formed between the restricting portion and the inner circumferential step portion in a state where the cushion ring and the contact portion are in contact with each other.

  In the fifth aspect of the invention, the supply / exhaust passage and the rod side chamber quickly communicate with each other during the contraction operation from the extension stroke end. Therefore, the responsiveness at the start of the contraction operation can be ensured.

  In a sixth aspect of the present invention, the cushion passage is formed in an orifice plug that is detachably provided on the cushion ring.

  According to the sixth aspect, the cushion performance can be easily adjusted by replacing the orifice plug.

  The seventh invention is characterized in that the restricting portion is a restricting pin that is inserted through the outer peripheral surface and the inner peripheral surface of the cushion ring so as to be movable in the radial direction.

  The eighth invention is characterized in that the restricting portions are a pair of restricting rings which are provided on the outer periphery and the inner periphery of the cushion ring, respectively, and are formed to be expandable and contractible.

  According to a ninth aspect of the present invention, the restricting portion is an expansion / contraction ring provided adjacent to the cushion ring in the axial direction and having an abutment gap so as to be expandable / contractible.

  In a tenth aspect of the invention, the cushion ring has a central recess formed on the inner side of the end face facing the regulating ring, the expansion / contraction ring has a central step portion inserted into the central recess, and the expansion / contraction ring is a piston rod. A radial gap is formed between the central concave portion and the central step portion in the state of being accommodated in the concave portion, and the central step portion is in contact with the central concave portion when the expansion / contraction ring is expanded and escapes from the concave portion. It is characterized by.

  In the tenth invention, the expansion / contraction ring is expanded while being aligned by contacting the central recess of the cushion ring and the central step of the expansion / contraction ring. Therefore, the slidability between the cushion ring and the expansion / contraction ring can be stabilized.

  According to the present invention, the fluid pressure cylinder can be reduced in size.

It is sectional drawing of the fluid pressure cylinder which concerns on 1st Embodiment of this invention. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention. It is a top view which shows the cushion ring of the fluid pressure cylinder which concerns on 1st Embodiment of this invention, (a) shows a 1st Example, (b) shows a 2nd Example. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and is a figure showing the length of a regulation pin. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the state where a piston rod exists near the stroke end at the time of extension operation. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the state where relative movement of the cushion ring with respect to a piston rod was permitted. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and is a figure showing the state of contraction operation from the stroke end of extension operation. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the state where the regulation pin opposed to the annular groove. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the modification in which a cushion passage is formed in a cushion ring. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the modification by which a cushion passage is formed in a piston rod. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the 1st modification by which a cushion passage is formed in a contact part. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 1st embodiment of the present invention, and shows the 2nd modification by which a cushion passage is formed in a contact part. It is an expanded sectional view showing a cushion part of a fluid pressure cylinder concerning a 2nd embodiment of the present invention. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 2nd embodiment of the present invention, and shows the 1st modification of a regulation ring. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 2nd embodiment of the present invention, and shows the 2nd modification of a regulation ring. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 2nd embodiment of the present invention, and shows the state where a piston rod exists near the stroke end at the time of extension operation. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 2nd embodiment of the present invention, and shows the state where relative movement of the cushion ring with respect to the piston rod was permitted. It is an expanded sectional view showing a cushion part of a fluid pressure cylinder concerning a 3rd embodiment of the present invention. It is a top view which shows the expansion / contraction ring of the fluid pressure cylinder which concerns on 3rd Embodiment of this invention. It is an expanded sectional view showing the cushion part of the fluid pressure cylinder concerning a 3rd embodiment of the present invention, and shows the state where a piston rod exists near the stroke end at the time of extension operation. It is an expanded sectional view showing a cushion part of a fluid pressure cylinder concerning a 3rd embodiment of the present invention, and is a figure showing a state which carries out contraction operation from a stroke end of extension operation. It is sectional drawing which shows the fluid pressure cylinder which concerns on the comparative example of this invention.

  Hereinafter, a fluid pressure cylinder according to an embodiment of the present invention will be described with reference to the drawings. Below, the case where a fluid pressure cylinder is a hydraulic cylinder which drives hydraulic oil as a working fluid is demonstrated.

(First embodiment)
As shown in FIG. 1, the hydraulic cylinder 100 according to the first embodiment includes a cylindrical cylinder tube 10, a piston rod 20 inserted into the cylinder tube 10, and a tip of the piston rod 20. A piston 30 that slides along the inner peripheral surface and a cushion portion 40 provided on the outer periphery of the piston rod 20 are provided.

  The inside of the cylinder tube 10 is partitioned by the piston 30 into two fluid pressure chambers of the rod side chamber 1 and the bottom side chamber 2. The hydraulic cylinder 100 is expanded and contracted by the hydraulic pressure guided from the hydraulic source (working fluid pressure source) to the rod side chamber 1 or the bottom side chamber 2. The space between the inner periphery of the cylinder tube 10 and the outer periphery of the piston 30 is sealed by a seal member (not shown). Thereby, the communication between the rod side chamber 1 and the bottom side chamber 2 between the inner periphery of the cylinder tube 10 and the outer periphery of the piston 30 is blocked.

  The inner peripheral surface of the cylinder tube 10 includes a sliding surface 11 on which the piston 30 slides, a large-diameter surface 12 formed with an inner diameter larger than the sliding surface 11, and the sliding surface 11 and the large-diameter surface 12. And an inner circumferential step portion 13 formed therebetween. The large diameter surface 12 is formed continuously from the opening 10 </ b> A at one end of the cylinder tube 10. The inner circumferential step 13 is formed with a tapered surface 13 </ b> A that decreases in inner diameter from the large-diameter surface 12 toward the sliding surface 11.

  The cylinder tube 10 is provided with a cylindrical cylinder head 50 that seals the opening 10A at one end and slidably supports the piston rod 20. The cylinder head 50 has a contact portion 51 that contacts the cushion portion 40 in the vicinity of the stroke end of the piston rod 20 during the extension operation. The contact portion 51 is formed in a cylindrical shape and is inserted inside the cylinder tube 10. The cylinder head 50 is fastened to the cylinder tube 10 via a plurality of fastening bolts (not shown) arranged in the circumferential direction.

  A bush 55, a sub seal 56, a main seal 57, and a dust seal 58 are interposed on the inner periphery of the cylinder head 50.

  When the bush 55 is in sliding contact with the outer peripheral surface of the piston rod 20, the piston rod 20 is supported so as to move in the axial direction of the cylinder tube 10.

  The cylinder head 50 is formed with a supply / discharge port 3 communicating with a hydraulic pressure source. The cylinder head 50 defines a supply / exhaust passage 4 that communicates the supply / exhaust port 3 and the rod side chamber 1 with the piston rod 20 by a passage groove 50 </ b> A formed on the inner peripheral surface. The hydraulic oil is supplied / discharged from the supply / discharge port 3 to the rod side chamber 1 through the supply / discharge passage 4.

  The piston rod 20 includes a main body portion 21 that is in sliding contact with the inner periphery of the cylinder head 50, a small diameter portion 22 that has a smaller outer diameter than the main body portion 21, and an annular shape that is formed between the main body portion 21 and the small diameter portion 22. It has a stepped portion 23 and a threaded portion 24 formed at the tip of the piston rod 20 to which the piston 30 is fastened.

  As shown in FIGS. 1 and 2, the small-diameter portion 22 has an annular groove 25 as a recess at a position adjacent to the step portion 23. The annular groove 25 has a groove taper portion 25A that is connected to the outer peripheral surface of the small-diameter portion 22 and has a depth that decreases toward the piston 30 side.

  The piston 30 is screwed into the threaded portion 24 of the piston rod 20, and is fastened to the piston rod 20 by a predetermined tightening force.

  The cushion portion 40 is provided on the outer periphery of the small diameter portion 22 of the piston rod 20 and between the step portion 23 and the piston 30 in the axial direction. As shown in FIGS. 2 and 3A, the cushion portion 40 includes a cushion ring 41 that defines a cushion passage 42 that provides resistance to the passing hydraulic oil, and is locked to the cushion ring 41 and is a piston rod. 20, and a restriction pin 45 as a restriction portion for restricting relative movement of the cushion ring 41 with respect to the piston rod 20 in a state where a part is accommodated in the annular groove 25 of the small diameter portion 22.

  As shown in FIG. 2, the cushion ring 41 is slidably fitted to the small diameter portion 22 of the piston rod 20. The cushion ring 41 is formed so that the outer diameter is smaller than the inner diameter of the sliding surface 11 of the cylinder tube 10.

  As shown in FIGS. 2 and 3A, the cushion ring 41 has a plurality of cushion passages 42 defined by a plurality of through holes penetrating in the axial direction. The cushion passage 42 communicates the rod side chamber 1 and the supply / discharge passage 4 even when the cushion ring 41 is in contact with the contact portion 51 (see FIG. 5). That is, the cushion passage 42 is formed so as to open at a position facing the supply / discharge passage 4 on the end face of the cushion ring 41 facing the cylinder head 50.

  Resistance is applied to the flow of hydraulic oil that passes through the cushion passage 42. When the hydraulic oil passes through the cushion passage 42, a cushion pressure acts on the rod side chamber 1. As a result, the hydraulic cylinder 100 exhibits a cushioning action that reduces the extension speed near the end of the extension stroke.

  A plurality of radial grooves 46 that extend in the radial direction and communicate with the cushion passage 42 are formed on the end surface of the cushion ring 41 that faces the piston 30. When the pressure of the hydraulic oil is guided to the radial groove 46, the separation from the contact state between the cushion ring 41 and the piston 30 during the contraction operation as described later is promoted.

  As shown in FIG. 3B, the radial groove 46 may not be communicated with the cushion passage 42 and may be formed at a position shifted from the cushion passage 42. Further, the radial groove 46 may open on the outer peripheral surface of the cushion ring 41. As described above, at least a part of the radial groove 46 is formed on the end face of the cushion ring 41 facing the piston 30 in the cushion ring 41, and guides the pressure of the hydraulic oil to separate the cushion ring 41 and the piston 30. As long as it is formed so as to promote, it can be formed in an arbitrary shape. 2 and 4 to 8, the cushion passage 42 and the radial groove 46 are schematically shown by broken lines.

  The cushion ring 41 is formed with an insertion hole 47 that opens to the inner peripheral surface and the outer peripheral surface. As shown in FIG. 2, the regulation pin 45 is inserted into the insertion hole 47 of the cushion ring 41 and passes through the inner and outer peripheral surfaces of the cushion ring 41 in the radial direction. The restriction pin 45 is inserted into the insertion hole 47 so as to be movable in the radial direction of the cushion ring 41.

  As shown in FIG. 4, the length L of the restriction pin 45 is longer than the radial width W <b> 1 of the annular space between the small diameter portion 22 of the piston rod 20 and the sliding surface 11 of the cylinder tube 10.

  Thus, when the regulation pin 45 moves toward the radially outer side in a state of facing the sliding surface 11 of the cylinder tube 10 and the end portion 45A on the radially outer side contacts the sliding surface 11, The state where the radially inner end 45B is accommodated in the annular groove 25 is maintained. For this reason, the escape of the regulation pin 45 from the annular groove 25 is regulated. Therefore, the cushion ring 41 is held by the piston rod 20 by the restriction pin 45, and the relative movement of the cushion ring 41 and the piston rod 20 in the axial direction is restricted. Note that “restricting relative movement in the axial direction” includes restricting relative movement between the cushion ring 41 and the piston rod 20 while the restriction pin 45 is housed in the annular groove 25. It is not intended to restrict the movement of the restriction pin 45 from the annular groove 25 and relative movement.

  Further, the length of the restriction pin 45 is shorter than the radial width W2 of the annular space defined between the large diameter surface 12 of the cylinder tube 10 and the small diameter portion 22 of the piston rod 20 (see FIG. 4). Therefore, when the regulation pin 45 is opposed to the large-diameter surface 12 of the cylinder tube 10, the restriction pin 45 moves radially outward so that the radially inner end 45 </ b> B can escape from the annular groove 25 (see FIG. 5). ). When the restricting pin 45 moves radially outward, the radially inner end 45B escapes from the annular groove 25, and the holding of the cushion ring 41 by the piston rod 20 is released. Thereby, the relative movement of the cushion ring 41 and the piston rod 20 in the axial direction is allowed. Further, in the state where the cushion ring 41 and the contact portion 51 are in contact, the restriction pin 45 is provided with an axial gap between the inner peripheral step portion 13 as shown in FIGS. 5 and 6.

  Next, the operation of the hydraulic cylinder 100 will be described.

  When a hydraulic pressure source communicates with the bottom side chamber 2 and a tank (not shown) communicates with the rod side chamber 1, hydraulic oil is supplied to the bottom side chamber 2, and the hydraulic oil in the rod side chamber 1 is discharged to the tank. For this reason, the hydraulic cylinder 100 is extended.

  As shown in FIG. 2, when the restriction pin 45 of the cushion portion 40 faces the sliding surface 11 of the cylinder tube 10 during the extension operation, the movement of the restriction pin 45 toward the radially outer side is the sliding surface 11. Regulated by. For this reason, the end portion 45 </ b> B on the radially inner side of the restriction pin 45 is maintained in a state of being accommodated in the annular groove 25. In other words, even if the radially inner end 45B of the restricting pin 45 tries to get over the groove taper portion 25A from the bottom of the annular groove 25 toward the small diameter portion 22, the radially outer end 45A first slides. 11, the restriction pin 45 does not escape from the annular groove 25. Therefore, in this state, the state in which the cushion ring 41 is held by the piston rod 20 is maintained, and the cushion portion 40 moves in the extending direction together with the piston rod 20. As the piston rod 20 moves in the extending direction, the hydraulic oil in the rod side chamber 1 is directly guided to the supply / discharge passage 4 and discharged through the supply / discharge port 3.

  When the piston rod 20 moves to the vicinity of the end of the extension stroke as shown in FIG. 5 due to the extension operation of the hydraulic cylinder 100, the restriction pin 45 faces the large diameter surface 12 of the cylinder tube 10 and the cushion ring 41 moves to the cylinder head 50. The contact part 51 is contacted. When the cushion ring 41 and the contact portion 51 come into contact, direct communication between the supply / discharge passage 4 and the rod-side chamber 1 is blocked.

  In the hydraulic cylinder 100, in the process of moving the piston rod 20 in the extending direction, the timing at which the restriction pin 45 faces the large diameter surface 12 is slightly smaller than the timing at which the cushion ring 41 and the contact portion 51 contact each other. Configured to be faster.

  When the piston rod 20 further moves in the extending direction from the state where the cushion ring 41 and the contact portion 51 are in contact with each other, the restriction pin 45 is guided by the groove taper portion 25A of the annular groove 25 and is pushed out radially outward. Moving. At this time, the large diameter surface 12 does not come into contact with the restriction pin 45 and restricts the movement of the restriction pin 45 and allows the restriction pin 45 to move outward in the radial direction.

  Therefore, as shown in FIG. 6, the radially inner end 45 </ b> B of the regulation pin 45 escapes from the annular groove 25 and the holding of the cushion ring 41 by the piston rod 20 is released, and the piston in the extending direction with respect to the cushion ring 41 is released. The relative movement of the rod 20 is allowed. As described above, the groove taper portion 25A formed in the annular groove 25 moves the regulating pin 45 in the radial direction along with the movement of the piston rod 20 in the extending direction from the state in which the cushion ring 41 and the contact portion 51 are in contact. It corresponds to an escape guide portion that is pushed outward to escape from the annular groove 25.

  When the piston rod 20 further moves in the extending direction, the hydraulic oil in the rod side chamber 1 between the cushion ring 41 and the piston 30 is guided to the supply / discharge passage 4 and the supply / discharge port 3 (see FIG. 1) through the cushion passage 42. It is discharged from the rod side chamber 1. Since resistance is applied to the flow of the hydraulic oil passing through the cushion passage 42, a cushion pressure corresponding to the resistance applied by the cushion passage 42 acts on the rod side chamber 1. Thus, the cushion function in the vicinity of the extension stroke end of the piston rod 20 is exhibited.

  When the hydraulic pressure source communicates with the rod side chamber 1 and the tank communicates with the bottom side chamber 2, the hydraulic oil is supplied to the rod side chamber 1 and the hydraulic oil in the bottom side chamber 2 is discharged to the tank. For this reason, the hydraulic cylinder 100 is contracted.

  When the contraction operation is performed from the end of the extension stroke at which the piston 30 is in contact with the cushion ring 41, first, the hydraulic oil guided from the supply / exhaust passage 4 is used for the axial clearance between the regulation pin 45 and the inner circumferential step portion 13. Both the cushion ring 41 and the piston rod 20 move in the contraction direction. Thus, by providing an axial gap between the regulation pin 45 and the inner circumferential step portion 13, in the contraction operation from the end of the extension stroke, the cushion ring 41 and the contact portion 51 are quickly separated, The supply / discharge passage 4 and the rod side chamber 1 can be directly communicated with each other. As a result, the hydraulic oil quickly flows into the rod side chamber 1 to ensure the responsiveness during the contraction operation.

  When the cushion ring 41 and the piston rod 20 are moved in the contraction direction by the axial clearance between the restriction pin 45 and the inner peripheral step portion 13, the restriction pin 45 and the inner peripheral step portion 13 come into contact with each other as shown in FIG. . At this time, since the end portion 45B on the radially inner side of the restriction pin 45 is in sliding contact with the outer peripheral surface of the small diameter portion 22 of the piston rod 20, the restriction pin 45 cannot move further inward in the radial direction. The portion 45A does not get over the inner circumferential step portion 13 toward the sliding surface 11 of the cylinder tube 10. For this reason, the cushion ring 41 is locked to the inner circumferential step 13 of the cylinder tube 10 by the restriction pin 45. In this state, the radial groove 46 is mainly formed through the gap between the supply / discharge passage 4, the contact portion 51 and the cushion ring 41, and the gap between the outer periphery of the cushion ring 41 and the inner peripheral surface of the cylinder tube 10. The pressure of the hydraulic oil is guided and acts on the end face of the piston 30. Thereby, the cushion ring 41 and the piston 30 are separated from each other, and the piston rod 20 moves relative to the cushion ring 41 in the contracting direction. In this way, the radial groove 46 functions as a pressure introducing groove, and promotes the separation between the cushion ring 41 and the piston 30 during the contraction operation. By providing the radial groove 46, it is possible to prevent the restriction pin 45 from being pressed against the inner circumferential step 13 of the cylinder tube 10 by the pressure of the hydraulic oil, and the regulation pin 45 and the inner circumferential step 13 from being damaged.

  As shown in FIG. 8, when the piston rod 20 moves in the contraction direction until the radially inner end 45 </ b> B of the restriction pin 45 faces the annular groove 25 of the piston rod 20, the restriction pin 45 moves inward in the radial direction. Is acceptable. When the cushion ring 41 receives the fluid force of the hydraulic oil supplied to the rod side chamber 1, the restricting pin 45 has a radially outer end 45 </ b> A guided by the tapered surface 13 </ b> A of the inner circumferential stepped portion 13, and the radially inner side. Pushed out. As a result, the restriction pin 45 is unlocked from the inner circumferential step portion 13 of the cylinder tube 10, and the radially inner end portion 45 </ b> B is accommodated in the annular groove 25 of the piston rod 20 again. In this way, the cushion ring 41 held again by the piston rod 20 moves in the contracting direction together with the piston rod 20. In this way, the taper surface 13A of the inner circumferential step 13 is moved radially inward with the movement of the piston rod 20 in the contracting direction from the state where the cushion ring 41 and the contact portion 51 are in contact. It corresponds to an accommodation guide portion that is pushed out and accommodated in the annular groove 25.

  As described above, in the hydraulic cylinder 100, the relative movement of the cushion ring 41 with respect to the piston rod 20 is restricted by the restriction pin 45, so that the cushion ring 41 and the piston rod 20 extend in the extending direction until the contact with the contact portion 51. Move to. In the vicinity of the stroke end during the extension operation, the cushion ring 41 is brought into contact with the contact portion 51 and the relative movement with the piston rod 20 is allowed, so that the cushion function is exhibited. Further, in the hydraulic cylinder 100, since the restriction pin 45 is accommodated again in the piston rod 20 during the contraction operation, the cushion ring 41 can be held again by the piston rod 20 and moved together with the piston rod 20 in the contraction direction. Therefore, without providing a spring in the rod side chamber 1, the cushion portion 40 and the piston rod 20 can be moved relative to each other when the cushion function is exerted, and can be moved together with the piston rod 20 in the contracting direction during the contracting operation. Therefore, the overall length of the hydraulic cylinder 100 can be shortened and downsized.

  Further, when a spring is provided in the rod side chamber 1, a pressure difference may be generated between the inside and the outside of the spring, particularly when the spring contracts and the axial gap between the wires becomes small. If the spring breaks due to such a pressure difference, the operation of the cushion portion 40 becomes unstable, and the cushion function may not be stably exhibited. On the other hand, since the hydraulic cylinder 100 does not provide a spring in the rod side chamber 1 and supports the cushion ring 41 by the restriction pin 45, the occurrence of a situation in which the cushion function is not stably exhibited due to breakage of the spring is prevented. Can do.

  Here, in order to facilitate understanding of the present invention, a hydraulic cylinder 400 according to a comparative example will be described with reference to FIG. About the same structure as the hydraulic cylinder 100, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The hydraulic cylinder 400 according to the comparative example includes a cylindrical cushion bearing 340 provided on the outer periphery of the piston rod 20 and a bearing receiving portion 351 that allows the cushion bearing 340 to enter in the vicinity of the extension stroke end.

  In the hydraulic cylinder 400, the cushion passage 342 is formed by the cushion bearing 340 entering the inside of the bearing receiving portion 351 near the end of the extension stroke. As the hydraulic oil in the rod side chamber 1 is discharged through the cushion passage 342, a cushion pressure corresponding to the resistance applied by the cushion passage 342 acts on the rod side chamber 1. In the hydraulic cylinder 400, the pressure receiving area of the piston 30 on which the cushion pressure acts corresponds to the area between the outer periphery of the cushion bearing 340 and the outer periphery of the piston 30.

  On the other hand, since the hydraulic cylinder 100 according to the present embodiment does not include the cushion bearing 340, the pressure receiving area of the cushion pressure is the area between the outer periphery of the small diameter portion 22 of the piston rod 20 and the outer periphery of the piston 30. Equivalent to. For this reason, the pressure receiving area of the hydraulic cylinder 100 can be made larger by the cross-sectional integral of the cushion bearing 340 than the pressure receiving area of the hydraulic cylinder 400 according to the comparative example. Therefore, in the hydraulic cylinder 100, even if the same cushion performance is exhibited, the pressure receiving area is increased, so that the cushion pressure can be made smaller than that of the hydraulic cylinder 400. Since the cushion pressure can be reduced, in the hydraulic cylinder 100, the strength of the cylinder tube 10, the piston 30, and the cylinder head 50 that receive the cushion pressure may be relatively small, and the manufacturing cost can be reduced.

  In some hydraulic cylinders 400 including the cushion bearing 340, the cushion bearing 340 is clamped in the axial direction by the step portion 23 of the piston rod 20 and the piston 30 screwed to the piston rod 20. In such a contraction operation from the end of the extension stroke of the hydraulic cylinder 400, the supply / discharge passage 4 and the rod side chamber 1 communicate with each other through the cushion passage 342 until the cushion bearing 340 comes out of the bearing receiving portion 351. When the cushion bearing 340 comes out of the bearing receiving portion 351, the flow area of the hydraulic oil is suddenly expanded, and sudden pressure fluctuations and fluctuations in the operating speed (moving speed of the piston 30) occur in the rod side chamber 1. May cause abnormal noise. On the other hand, in the hydraulic cylinder 100 according to the present embodiment, the cushion ring 41 and the contact portion 51 are quickly separated and the supply / exhaust passage 4 and the rod side chamber 1 directly communicate with each other. Occurrence of abnormal noise or the like due to speed fluctuation can be prevented.

  In the hydraulic cylinder 400 including the cushion bearing 340, the cushion bearing 340 is provided with a gap in the axial direction between the step portion 23 of the piston rod 20 and the piston 30 screwed to the piston rod 20 (so-called Floating support structure). In such a hydraulic cylinder 400, a groove is formed on the outer peripheral surface of the piston rod 20, and a cushion seal having a joint gap may be provided in the groove of the piston rod 20. In the hydraulic cylinder 400, the hydraulic oil in the rod side chamber 1 exerts a cushion function by imparting resistance to the hydraulic oil by the cushion passage 342 and the joint gap of the cushion seal. When a cushion seal is provided inside the cushion bearing 340, the cushion performance of the hydraulic cylinder 400 can be easily adjusted by adjusting the size of the joint gap with the cushion bearing 340 in common.

  On the other hand, in the hydraulic cylinder 100, the cushion performance can be easily adjusted by adjusting the size of the cushion passage 42. Therefore, it is not necessary to form the cushion seal and the groove of the piston rod 20 that accommodates the cushion seal. . Therefore, in the hydraulic cylinder 100, the cushion performance can be easily adjusted, and the number of processing steps can be reduced, so that the manufacturing cost can be further reduced.

  Next, a modification of the first embodiment will be described.

  In the first embodiment, the cushion passage 42 is a through hole formed in the cushion ring 41. Instead of this, the cushion passage 42 may be formed in an orifice plug that is detachably attached to the cushion ring 41. In this case, by preparing a plurality of orifice plugs in which the cushion passages 42 having different diameters are prepared, the cushion performance can be easily adjusted, and the cushion ring 41 can be used in common, thereby reducing the manufacturing cost. be able to. Also, by preparing an orifice plug in which the cushion passage 42 is formed and a sealing plug in which the cushion passage 42 is not formed, the number of orifice plugs and sealing plugs attached to the cushion ring 41 can be arbitrarily changed. The cushion performance may be adjusted.

  The cushion passage 42 may be a single through hole. Furthermore, the cushion passage 42 may not be a through hole. For example, an annular passage defined by the outer peripheral surface of the piston rod 20 and the inner peripheral surface of the cushion ring 41 may be used as the cushion passage 42. Further, as shown in FIG. 9, the cushion passage 42 may be a slit formed on the end surface of the cushion ring 41 facing the contact portion 51.

  The cushion passage 42 is preferably formed in the cushion ring 41. Since the cushion ring 41 is smaller than the piston rod 20 and the cylinder head 50 and has a size that is easy to process, the cushion passage 42 can be easily formed with high accuracy. However, the cushion passage 42 may be formed in the piston rod 20, for example, as shown in FIG. As shown in FIGS. 11 and 12, the cushion passage 42 may be a passage or slit formed in the contact portion 51.

  Further, the recess may not be the annular groove 25 and can be formed in an arbitrary shape as long as it accommodates the regulation pin 45. For example, the recess may be a recess formed in a part in the circumferential direction, instead of an annular shape over the entire circumference of the piston rod 20. A plurality of restriction pins 45 may be provided. By providing the plurality of restricting pins 45, it is possible to disperse the force acting on each restricting pin 45 when being locked to the recess 25 or the inner circumferential step portion 13.

  Further, in the first embodiment, the escape guide portion is the groove taper portion 25 </ b> A of the annular groove 25 of the piston rod 20, and the accommodation guide portion is the taper surface 13 </ b> A of the inner circumferential step portion 13 of the cylinder tube 10. On the other hand, the escape guide portion and the accommodation guide portion may be formed on the restriction pin 45, respectively. Further, the escape guide portion and the accommodation guide portion may be formed in each of the regulation pin 45, the annular groove 25, and the inner circumferential step portion 13. Furthermore, the escape guide part and the accommodation guide part are not limited to the tapered surface, and may be any one that presses and pushes out the regulating pin 45 in the radial direction as the piston rod 20 moves, and may be, for example, a curved surface. For example, the radially outer end 45A and the inner end 45B of the restriction pin 45 may be formed in a hemispherical shape, and the spherical surfaces of the ends 45A and 45B may be used as the escape guide portion and the accommodation guide portion.

  According to the above 1st Embodiment, there exists an effect shown below.

  In the hydraulic cylinder 100, when the cushion ring 41 comes into contact with the contact portion 51 in the vicinity of the stroke end during the extension operation, direct communication between the supply / discharge passage 4 and the rod side chamber 1 is blocked. When the piston rod 20 further moves in the extending direction from the state in which the cushion ring 41 and the contact portion 51 are in contact with each other, relative movement between the piston rod 20 and the cushion ring 41 that has been restricted by the restriction pin 45 is allowed. . Therefore, in the vicinity of the stroke end of the extension operation, the hydraulic oil discharged from the rod side chamber 1 is guided to the supply / discharge passage 4 through the cushion passage 42, and a cushion function for decelerating the piston rod 20 is exhibited. As described above, the cushion ring 41 is held by the piston rod 20 by the restriction pin 45, so that a spring for supporting the cushion ring 41 is not provided in the rod side chamber 1, and in the vicinity of the stroke end during the extension operation, The cushion function is demonstrated. Therefore, the hydraulic cylinder 100 can be reduced in size.

  Further, since the hydraulic cylinder 100 does not need to provide a spring for supporting the cushion ring 41 in the rod side chamber 1, the operation of the cushion portion 40 is prevented from becoming unstable due to breakage of the spring, and the cushion is stably cushioned. Function can be demonstrated.

  Further, since the hydraulic cylinder 100 does not define the cushion passage 341 by the cushion bearing 340 that enters the bearing receiving portion 351, a cushion seal inside the cushion bearing 340 is not necessary, and the manufacturing cost can be reduced. Further, it is possible to prevent the generation of abnormal noise when the cushion bearing 340 comes out of the bearing receiving portion 351.

  Further, since the hydraulic cylinder 100 does not require the cushion bearing 340, the pressure receiving area for receiving the cushion pressure in the cylinder head 50 and the piston 30 can be increased as compared with the case where the cushion passage 341 is defined by the cushion bearing 340. it can. For this reason, cushion pressure can be reduced and the cylinder tube 10, the cylinder head 50, and piston 30 can be formed in comparatively low intensity | strength. Therefore, the manufacturing cost can be reduced.

(Second Embodiment)
Next, a hydraulic cylinder 200 according to a second embodiment of the present invention will be described with reference to FIGS. Below, it demonstrates centering on a different point from the said 1st Embodiment, the same code | symbol is attached | subjected to the structure same as the hydraulic cylinder 100 of the said 1st Embodiment, and description is abbreviate | omitted.

  In the first embodiment, the restricting portion is the restricting pin 45 that passes through the inner peripheral surface and the outer peripheral surface of the cushion ring 41.

  In contrast, the hydraulic cylinder 200 according to the second embodiment has a pair of restriction rings 145 provided on the outer periphery and the inner periphery of the cushion ring 141, respectively, in the hydraulic cylinder 100 according to the first embodiment. Is different.

  As shown in FIG. 13, an outer peripheral groove 141 </ b> A and an inner peripheral groove 141 </ b> B formed in an annular shape are provided on the outer peripheral surface and the inner peripheral surface of the cushion ring 141 of the hydraulic cylinder 200, respectively. The cushion ring 141 is formed with the cushion passage 42 and the radial groove 46 as in the first embodiment, and the resistance given to the hydraulic oil is smaller than the resistance given by the cushion passage 42 to the hydraulic oil. A plurality of main passages 142 are formed. When the cushion ring 141 contacts the contact portion 51, the main passage 142 is blocked by the contact portion 51 (see FIG. 16). 13 to 17, only the single main passage 142 is illustrated, and the others are not illustrated.

  The pair of regulating rings 145 includes an outer peripheral ring 145A provided in the outer peripheral groove 141A of the cushion ring 141 and an inner peripheral ring 145B provided in the inner peripheral groove 141B.

  The outer ring 145A and the inner ring 145B are each formed into a C-ring shape that has a joint gap (not shown) and can be expanded and contracted. The outer ring 145A and the inner ring 145B may be made of metal such as a snap ring or may be made of resin. In the present embodiment, the outer ring 145A and the inner ring 145B have a circular cross section as shown in FIG. 13, but the present invention is not limited to this, and other cross sectional shapes (for example, a rectangular shape shown in FIG. 14). It may have. Further, as shown in FIG. 15, urging members 145C and 145D such as rubber are provided between the outer ring 145A and the outer groove 141A and between the inner ring 145B and the inner groove 141B, so that the outer ring 145A has a diameter. The inner peripheral ring 145B may be urged radially inward by urging in the direction outward.

  The outer peripheral ring 145 </ b> A contacts the inner peripheral surface of the cylinder tube 10, and further expansion is restricted by the inner peripheral surface of the cylinder tube 10. In other words, the outer peripheral ring 145A protrudes radially outward from the outer peripheral groove 141A in a free state, and is accommodated in the outer peripheral groove 141A by being pressed and contracted radially inward by the inner peripheral surface of the cylinder tube 10. .

  The inner peripheral ring 145 </ b> B contacts the outer peripheral surface of the piston rod 20, and further contraction is restricted by the outer peripheral surface of the piston rod 20. In other words, the inner peripheral ring 145B protrudes radially inward from the inner peripheral groove 141B in a free state, and is accommodated in the inner peripheral groove 141B by being pressed and expanded radially outward by the outer peripheral surface of the piston rod 20. Is done.

  In the hydraulic cylinder 200, the outer ring 145A is in contact with the inner peripheral surface of the cylinder tube 10 and the inner ring 145B is in contact with the outer peripheral surface of the piston rod 20, so that the rod side chamber 1 is connected to the first rod side chamber 1A by the cushion portion 140. It is partitioned into a second rod side chamber 1B. The first rod side chamber 1 </ b> A and the second rod side chamber 1 </ b> B communicate with each other through the main passage 142 of the cushion ring 141.

  In a state where the outer peripheral ring 145 </ b> A faces the sliding surface 11 of the cylinder tube 10, the inner peripheral portion of the inner peripheral ring 145 </ b> B is accommodated in the annular groove 25 of the piston rod 20, and the cushion ring 141 is held by the piston rod 20. More specifically, the inner ring 145B accommodated in the inner groove 141B in a state of being expanded by the outer peripheral surface of the piston rod 20 is restricted from escaping from the annular groove 25 by the elastic force in the contracting direction. The Thereby, the state in which the cushion ring 141 is held by the piston rod 20 is maintained, and the relative movement in the axial direction between the cushion ring 141 and the piston rod 20 is restricted.

  As shown in FIG. 13, when the cushion portion 140 is opposed to the sliding surface 11 of the cylinder tube 10 during the extension operation, the state where the inner peripheral ring 145B is accommodated in the annular groove 25 is maintained. The state in which the ring 141 is held by the piston rod 20 is maintained. Therefore, the cushion ring 141 moves in the extending direction together with the piston rod 20 while the outer ring 145A is in sliding contact with the sliding surface 11 of the cylinder tube 10. With the movement of the piston rod 20, the hydraulic oil in the first rod side chamber 1 </ b> A is directly guided to the supply / discharge passage 4 and discharged through the supply / discharge port 3.

  When the piston rod 20 moves to the vicinity of the extension stroke end as shown in FIG. 16, the outer peripheral ring 145 </ b> A of the cushion portion 140 faces the large-diameter surface 12 of the cylinder tube 10, and the cushion ring 141 is the contact portion of the cylinder head 50. 51 abuts.

  When the outer peripheral ring 145 </ b> A accommodated in the outer peripheral groove 141 </ b> A in a contracted state is opposed to the large-diameter surface 12, the outer peripheral ring 145 </ b> A expands by elastic force and contacts the large-diameter surface 12. When the cushion ring 141 and the contact portion 51 come into contact with each other, direct communication between the supply / discharge passage 4 and the first rod side chamber 1A is blocked. Further, since the main passage 142 is blocked by the contact portion 51, the communication between the second rod side chamber 1B and the supply / discharge passage 4 through the main passage 142 is also blocked.

  When the piston rod 20 further moves in the extending direction from the state in which the cushion ring 141 and the contact portion 51 are in contact with each other, the inner peripheral ring 145B is guided by the groove taper portion 25A of the annular groove 25 and pressed outward in the radial direction. The As a result, as shown in FIG. 17, the inner peripheral ring 145 </ b> B is expanded against the elastic force in the contraction direction and escapes from the annular groove 25. Accordingly, the holding of the cushion ring 141 by the piston rod 20 is released, and the relative movement of the piston rod 20 in the extending direction with respect to the cushion ring 141 is allowed.

  When the piston rod 20 further moves in the extending direction, the hydraulic oil in the second rod side chamber 1B is guided to the supply / discharge passage 4 and the supply / discharge port 3 through the cushion passage 42 and discharged. Therefore, a cushion pressure corresponding to the resistance applied by the cushion passage 42 acts on the second rod side chamber 1. Thus, the cushion function in the vicinity of the extension stroke end of the piston rod 20 is exhibited.

  When the contraction operation is performed from the end of the extended stroke, as in the first embodiment, the cushion oil is provided by the amount of axial clearance between the outer ring 145A and the inner step 13 by the hydraulic oil guided from the supply / discharge passage 4. Both 141 and the piston rod 20 move in the contraction direction. Thereby, the cushion ring 141 and the contact portion 51 are separated from each other, and the supply / discharge passage 4 and the first rod side chamber 1A are directly communicated with each other.

  When the cushion ring 141 and the piston rod 20 move in the contraction direction by the axial clearance between the outer ring 145A and the inner circumferential step portion 13, the outer ring 145A and the inner circumferential step portion 13 come into contact with each other. At this time, the outer ring 145 </ b> A is maintained in a state of being locked with the inner circumferential step 13 by the elastic force in the expansion direction, and does not get over the inner circumferential step 13 toward the sliding surface 11 of the cylinder tube 10. . For this reason, the cushion ring 141 is locked to the inner peripheral step 13 through the outer ring 145A. Therefore, the pressure of the hydraulic fluid guided from the supply / discharge passage 4 is guided to the radial groove 46 through the first rod side chamber 1A, the main passage 142, and the second rod side chamber 1B, and acts on the end face of the piston 30. As a result, the cushion ring 141 and the piston 30 are separated from each other, and the piston rod 20 moves relative to the cushion ring 141 in the contracting direction.

  When the piston rod 20 moves in the contraction direction until the inner circumferential ring 145B faces the annular groove 25 of the piston rod 20, the inner circumferential ring 145B is contracted by the elastic force and is accommodated in the annular groove 25. Further, the cushion ring 141 abuts on the step portion 23 of the piston rod 20. Accordingly, when the piston rod 20 further moves in the contraction direction, the cushion ring 141 also tries to move in the contraction direction, so that the outer ring 145 </ b> A resists the elastic force in the expansion direction and the tapered surface of the inner peripheral step portion 13. It is pressed radially inward by 13A and contracts. As a result, the engagement between the outer peripheral ring 145A and the inner peripheral step 13 of the cylinder tube 10 is released, and the cushion ring 141 moves together with the piston rod 20 in the contracting direction.

  According to the above 2nd Embodiment, there exists an effect similar to the said 1st Embodiment.

  Further, in the hydraulic cylinder 200, since the entire inner periphery of the inner peripheral ring 145B is accommodated in the annular groove 25, the contact between the inner peripheral ring 145B and the annular groove 25 is a line contact. For this reason, compared with the said 1st Embodiment with which the edge part 45B of the radial inside of the control pin 45 and the annular groove 25 contact like a point contact, the force which escapes the inner peripheral ring 145B from the annular groove 25 is provided. It can be dispersed and the durability can be improved.

  In the second embodiment, the restricting portion is a pair of restricting rings (an outer ring 145A and an inner ring 145B), but instead of this, the biasing members 145C and 145D (see FIG. 15) are used in the radial direction. One or a plurality of spheres (steel balls or the like) that are urged to the outside and the inside may be used as the restricting portion.

(Third embodiment)
Next, a hydraulic cylinder 300 according to a third embodiment of the present invention will be described with reference to FIGS. Below, it demonstrates centering on a different point from the said 1st Embodiment, the same code | symbol is attached | subjected to the structure same as the hydraulic cylinder 100 of the said 1st Embodiment, and description is abbreviate | omitted.

  In the first embodiment, the restricting portion is the restricting pin 45 that passes through the inner peripheral surface and the outer peripheral surface of the cushion ring 41.

  In contrast, the restricting portion of the hydraulic cylinder 300 according to the third embodiment is a single expansion / contraction ring 245 that is provided adjacent to the cushion ring 241 and has an abutment gap 245A and can be expanded / contracted. This is different from the hydraulic cylinder 100 according to the first embodiment.

  As shown in FIG. 18, the cushion ring 241 of the hydraulic cylinder 300 is provided between the step portion 23 of the piston rod 20 and the expansion / contraction ring 245. A cushion passage 242 and a radial groove 46 are formed in the cushion ring 241 as in the first embodiment, and an annular central recess 243 is formed radially inward at the end face facing the expansion / contraction ring 245. The cushion passage 242 is formed in communication with the space inside the central recess 243. The central recess 243 opens on the end surface of the cushion ring 241 facing the expansion / contraction ring 245 and opens on the inner peripheral surface of the cushion ring 241. When the cushion passage 242 is formed in the orifice plug attached to and detached from the cushion ring 241, the expansion / contraction ring 245 adjacent in the axial direction functions as a pressing member that prevents the orifice plug from coming off from the cushion ring 241.

  As shown in FIG. 19, the expansion / contraction ring 245 is formed in a C-ring shape having a gap 245A and capable of expansion / contraction. In the state where the expansion / contraction ring 245 faces the sliding surface 11 of the cylinder tube 10 (the state shown in FIG. 18), the inner peripheral portion is accommodated in the annular groove 25 as shown in FIG. A gap is formed in

  On the end face of the expansion / contraction ring 245 facing the cushion ring 241, as shown in FIGS. 18 and 19, there is a central step 246 that is inserted inside the central recess 243 while the expansion / contraction ring 245 is in contact with the cushion ring 241. It is formed.

  The outer diameter of the central step 246 is formed to be smaller than the inner diameter of the central recess 243 of the cushion ring 241 when the expansion / contraction ring 245 is accommodated in the annular groove 25. Therefore, in the state where the expansion / contraction ring 245 is accommodated in the annular groove 25, a radial gap is provided between the central recess 243 of the cushion ring 241 and the central step 246 of the expansion / contraction ring 245. Further, when the cushion ring 241 and the expansion / contraction ring 245 are in contact with each other, the central step portion 246 forms a gap in the axial direction without contacting the central concave portion 243. Therefore, the cushion passage 242 communicates with the joint gap 245A (see FIG. 19) of the expansion / contraction ring 245 through the radial gap and the axial gap between the central step 246 and the central recess 243.

  When the expansion / contraction ring 245 expands, the central step 246 comes into contact with the central recess 243 of the cushion ring 241. As described above, the center step 246 of the expansion / contraction ring 245 contacts the central recess 243 of the cushion ring 241, thereby preventing the center of the expansion / contraction ring 245 from being shifted from the center of the piston rod 20. In other words, the central recess 243 of the cushion ring 241 exhibits a centering function that prevents the centering of the expansion / contraction ring 245 accompanying expansion and stabilizes the slidability between the expansion / contraction ring 245 and the cushion ring 241.

  In a state where the expansion / contraction ring 245 faces the sliding surface 11 of the cylinder tube 10, the expansion / contraction ring 245 is accommodated in the annular groove 25 of the piston rod 20 so that the cushion ring 241 is sandwiched between the stepped portion 23 of the piston rod 20. Lock to 241. Thereby, the cushion ring 241 is held by the piston rod 20. The expansion / contraction ring 245 has an outer diameter smaller than the inner diameter of the sliding surface 11 when the inner peripheral surface is in contact with the annular groove 25 (the state shown in FIG. 18). In addition, the expansion / contraction ring 245 has an outer diameter that is larger than the inner diameter of the sliding surface 11 and smaller than the inner diameter of the large-diameter surface 12 in a state where it has escaped from the annular groove 25 (the state shown in FIG. 20). In a state where the inner peripheral surface of the expansion / contraction ring 245 contacts the annular groove 25, a gap is formed between the outer peripheral surface of the expansion / contraction ring 245 and the sliding surface 11 of the cylinder tube 10.

  As shown in FIG. 18, when the expansion / contraction ring 245 faces the sliding surface 11 of the cylinder tube 10, the expansion of the expansion / contraction ring 245 is restricted by the sliding surface 11, and the expansion / contraction ring 245 escapes from the annular groove 25. Be regulated.

  In a state where the expansion / contraction ring 245 faces the large diameter surface 12 of the cylinder tube 10, the expansion / contraction ring 245 is allowed to expand by the large diameter surface 12, and the expansion / contraction ring 245 can be removed from the annular groove 25. Therefore, as shown in FIG. 20, the cushion ring 241 is released from the holding by the piston rod 20 when the expansion / contraction ring 245 expands and escapes from the annular groove 25.

  At the time of extension operation, as shown in FIG. 18, in the state where the cushion portion 240 faces the sliding surface 11 of the cylinder tube 10, the expansion of the expansion / contraction ring 245 of the cushion portion 240 is regulated by the sliding surface 11. The state in which the expansion / contraction ring 245 is accommodated in the annular groove 25 is maintained. Therefore, the cushion ring 241 is maintained in the state where it is held by the piston rod 20 and moves in the extending direction together with the piston rod 20. As the piston rod 20 moves, the hydraulic oil in the rod side chamber 1 is directly guided to the supply / discharge passage 4 and discharged through the supply / discharge port 3.

  When the piston rod 20 moves to the vicinity of the extension stroke end, the expansion / contraction ring 245 of the cushion portion 40 faces the large-diameter surface 12 of the cylinder tube 10 and the cushion ring 241 contacts the contact portion 51 of the cylinder head 50.

  When the cushion ring 241 and the contact portion 51 come into contact with each other, direct communication between the supply / discharge passage 4 and the rod side chamber 1 is blocked.

  When the piston rod 20 further moves in the extending direction from the state where the cushion ring 241 and the contact portion 51 are in contact, the expansion / contraction ring 245 is guided by the groove taper portion 25A of the annular groove 25 as shown in FIG. It is pressed radially outward. Thereby, the expansion / contraction ring 245 expands and escapes from the annular groove 25. Accordingly, the holding of the cushion ring 241 by the piston rod 20 is released, and the relative movement of the piston rod 20 in the extending direction with respect to the cushion ring 241 is allowed.

  When the piston rod 20 further moves in the extending direction, the hydraulic oil in the rod side chamber 1 becomes a gap in the radial direction between the joint gap 245A of the expansion / contraction ring 245 and the central step 246 of the expansion / contraction ring 245 and the central recess 243 of the cushion ring 241. And the axial clearance and is guided to the cushion passage 242. The hydraulic oil in the rod side chamber 1 is guided to the supply / discharge passage 4 and the supply / discharge port 3 through the cushion passage 242 and is discharged from the rod side chamber 1. Therefore, a cushion pressure corresponding to the resistance applied by the cushion passage 242 acts on the rod side chamber 1. In this way, the cushioning action in the vicinity of the extension stroke end of the piston rod 20 is exhibited.

  When the contraction operation is performed from the end of the extension stroke, as in the first embodiment, the cushion oil is provided by an amount corresponding to the axial clearance between the expansion / contraction ring 245 and the inner circumferential step portion 13 by the hydraulic oil guided from the supply / discharge passage 4. Both 241 and the piston rod 20 move in the contraction direction. Accordingly, as shown in FIG. 21, the cushion ring 241 and the contact portion 51 are separated from each other, and the supply / discharge passage 4 and the first rod side chamber 1A are directly communicated with each other.

  When the cushion ring 241 and the piston rod 20 move in the contraction direction by the axial clearance between the expansion / contraction ring 245 and the inner circumferential step portion 13, the expansion / contraction ring 245 and the inner circumferential step portion 13 come into contact with each other. At this time, the expansion / contraction ring 245 cannot contract because the inner peripheral surface faces the small diameter portion 22 of the piston rod 20 (see FIG. 20). Since the expansion / contraction ring 245 does not get over the inner peripheral step 13 toward the sliding surface 11 of the cylinder tube 10, the cushion ring 241 is locked to the inner peripheral step 13 through the expansion / contraction ring 245.

  Therefore, the pressure of the hydraulic fluid guided from the supply / discharge passage 4 is guided to the radial groove 46 through the joint gap 245A of the rod side chamber 1 and the expansion / contraction ring 245 and acts on the end face of the piston 30. Thereby, the cushion ring 241 and the piston 30 are separated from each other, and the piston rod 20 moves relative to the cushion ring 241 in the contracting direction.

  When the piston rod 20 moves in the contraction direction until the expansion / contraction ring 245 faces the annular groove 25 of the piston rod 20, the expansion / contraction ring 245 is pressed radially inward by the tapered surface 13 </ b> A of the inner circumferential step portion 13 and its own. It contracts by the elastic force and is accommodated in the annular groove 25. As a result, the engagement between the expansion / contraction ring 245 and the inner circumferential step portion 13 of the cylinder tube 10 is released, and the expansion / contraction ring 245 is accommodated again in the annular groove 25 of the piston rod 20. In this way, the cushion ring 241 held again by the piston rod 20 moves in the contracting direction together with the piston rod 20.

  According to the above 3rd Embodiment, there exists an effect similar to the said 1st Embodiment.

  Similarly to the second embodiment, in the hydraulic cylinder 300, since the entire inner periphery of the expansion / contraction ring 245 is accommodated in the annular groove 25, the expansion / contraction ring 245 is formed in the annular groove 25 as compared with the first embodiment. It is possible to disperse the force of escaping from the environment and improve the durability.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  The hydraulic cylinders 100, 200, and 300 include a cylinder tube 10, a piston rod 20 inserted into the cylinder tube 10, and a piston that is connected to the tip of the piston rod 20 and divides the cylinder tube 10 into a rod side chamber 1 and a bottom side chamber. 30, cushion portions 40, 140, 240 provided on the outer periphery of the piston rod 20 and decelerating the piston rod 20 in the vicinity of the stroke end during the extension operation, and the working fluid that communicates with the rod side chamber 1 and is supplied to and discharged from the rod side chamber 1 , And a contact portion 51 that is provided in the cylinder tube 10 and abuts against the cushion portion 40 in the vicinity of the stroke end during the extension operation. The cushion portions 40, 140, and 240 are provided during the extension operation. Cushion rings 41, 141, 241 that contact the contact portion 51 near the stroke end of A restricting portion (a restricting pin 45, a pair of restricting rings 145, expansion / contraction) that restricts relative movement of the cushion rings 41, 141, 241 relative to the piston rod 20 in a state of being accommodated in an annular groove 25 formed on the outer peripheral surface of the stone rod 20. And the communication between the supply / discharge passage 4 and the rod side chamber 1 as the cushion rings 41, 141, 241 and the contact portion 51 come into contact with each other near the stroke end during the extension operation. Are blocked by the cushion rings 41, 141, 241, and the restricting portions (the restricting pins 45, the pair of restricting rings 145, the expansion / contraction ring 245) escape from the annular groove 25 and the cushion rings 41, 141, 241 with respect to the piston rod 20 Relative movement is allowed and the rod is passed through the cushion passages 42 and 242 which give resistance to the passing hydraulic oil. Hydraulic oil chamber 1 is discharged from the supply and discharge passage 4.

  In the hydraulic cylinders 100, 200, and 300, the inner peripheral surface of the cylinder tube 10 includes a sliding surface 11 on which the piston 30 slides, a large-diameter surface 12 that has a larger inner diameter than the sliding surface 11, The restricting portion (the restricting pin 45, the pair of restricting rings 145, and the expansion / contraction ring 245) is restricted from coming out of the annular groove 25 by contact with the sliding surface 11, and faces the large diameter surface 12. Thus, escape from the annular groove 25 is allowed.

  In these configurations, when the cushion portions 40, 140, 240 abut against the abutment portion 51 near the stroke end during the extension operation, direct communication between the supply / discharge passage 4 and the rod side chamber 1 is blocked. When the piston rod 20 further moves in the extending direction from the state in which the cushion portions 40, 140, 240 and the contact portion 51 are in contact, the restriction portions (the restriction pin 45, the pair of restriction rings 145, and the expansion / contraction ring 245). The relative movement between the regulated piston rod 20 and the cushion rings 41, 141, 241 is allowed. Therefore, in the vicinity of the stroke end of the extension operation, the hydraulic oil discharged from the rod side chamber 1 is guided to the supply / discharge passage 4 through the cushion passages 42 and 242, and the cushion function for decelerating the piston rod 20 is exhibited. As described above, the relative movement of the cushion rings 41, 141, 241 with respect to the piston rod 20 is restricted by the restriction portions (the restriction pins 45, the pair of restriction rings 145, the expansion / contraction ring 245), thereby the cushion rings 41, 141, 241. Even if the rod side chamber 1 is not provided with a spring for supporting it, the cushion function is exhibited in the vicinity of the stroke end during the extension operation. Therefore, the fluid pressure cylinders 100, 200, and 300 can be reduced in size.

  Further, in the hydraulic cylinders 100, 200, and 300, the cushion rings 41, 141, and 241 and the contact portion 51 are provided in at least one of the restriction portion (the restriction pin 45, the pair of restriction rings 145, the expansion / contraction ring 245) or the annular groove 25. In accordance with the movement of the piston rod 20 in the extending direction from the state of contact with the groove, the restricting portion (the restricting pin 45, the inner peripheral ring 145B, the expansion / contraction ring 245) is pressed radially outward to escape from the annular groove 25. A tapered portion 25A is formed.

  According to this configuration, with the movement of the piston rod 20 in the extending direction from the state in which the cushion rings 41, 141, 241 and the contact portion 51 are in contact with each other, the restriction portion (the restriction pin 45, the inner peripheral ring 145 B, expansion / contraction) The ring 245) can surely escape from the annular groove 25.

  Further, in the hydraulic cylinders 100, 200, and 300, the inner peripheral surface of the cylinder tube 10 further includes an inner peripheral step 13 formed between the sliding surface 11 and the large-diameter surface 12. At least one of the pin 45, the outer ring 145A, the expansion / contraction ring 245) or the inner step 13 is in the contraction direction of the piston rod 20 from the state in which the cushion rings 41, 141, 241 and the contact portion 51 are in contact. Accompanying the movement, an accommodation guide portion is formed in which the restriction portions (restriction pin 45, outer ring 145A, expansion / contraction ring 245) are pressed radially inward to be accommodated in the annular groove 25.

  According to this configuration, with the movement of the piston rod 20 in the contracting direction from the state in which the cushion rings 41, 141, 241 and the contact portion 51 are in contact, the restriction portions (the restriction pin 45, the outer ring 145 </ b> A, the expansion / contraction ring). 245) can be reliably accommodated in the annular groove 25, and the piston rod 20 can be moved in the contraction direction.

  Further, in the hydraulic cylinders 100, 200, and 300, when the cushion ring 41 and the contact portion 51 are in contact with each other, the restriction portion (the restriction pin 45, the outer ring 145 </ b> A, the expansion / contraction ring 245) and the inner step portion 13. A gap in the axial direction is formed between them.

  In this configuration, the supply / exhaust passage 4 and the rod-side chamber 1 quickly communicate with each other during the contraction operation from the extension stroke end. Therefore, the responsiveness at the start of the contraction operation can be ensured.

  In the hydraulic cylinders 100, 200, and 300, the cushion passages 42 and 242 may be formed as orifice plugs that are detachably provided on the cushion rings 41, 141, and 241.

  According to this configuration, the cushion performance can be easily adjusted by exchanging the orifice plug.

  In the hydraulic cylinder 100, the restricting portion is a restricting pin 45 that is inserted through the outer peripheral surface and the inner peripheral surface of the cushion ring 41 and is movable in the radial direction.

  Further, in the hydraulic cylinder 200, the restricting portions are provided on the outer periphery and the inner periphery of the cushion ring 141, respectively, and a pair of restricting rings 145 (an outer ring 145A and an inner ring 145B) are formed so as to be able to expand and contract. It is.

  Further, in the hydraulic cylinder 300, the restricting portion is an expansion / contraction ring 245 provided adjacent to the cushion ring 241 in the axial direction and formed so as to be expandable / contractable with a joint gap 245A.

  In the hydraulic cylinder 300, the cushion ring 241 has a central recess 243 formed on the inner side of the end surface facing the expansion / contraction ring 245, and the expansion / contraction ring 245 has a central step 246 inserted into the central recess 243. In the state in which the expansion / contraction ring 245 is accommodated in the annular groove 25 of the piston rod 20, a radial gap is formed between the central recess 243 and the central step 246, and the expansion / contraction ring 245 expands to form the annular groove 25. In the state of having escaped from the center step 246, the central step 246 contacts the central recess 243.

  In this configuration, the expansion / contraction ring 245 can be expanded while being aligned by contacting the central recess 243 of the cushion ring 241 and the central step 246 of the expansion / contraction ring 245. Therefore, the slidability between the cushion ring 41 and the expansion / contraction ring 245 can be stabilized.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  DESCRIPTION OF SYMBOLS 100, 200, 300 ... Hydraulic cylinder (fluid pressure cylinder), 1 ... Rod side chamber, 2 ... Bottom side chamber, 4 ... Supply / discharge passage, 10 ... Cylinder tube, 11 ... Sliding surface, 12 ... Large diameter surface, 13 ... Inside Circumferentially stepped portion, 13A ... taper surface (accommodating guide portion), 20 ... piston rod, 25 ... annular groove (recessed portion), 25A ... groove tapered portion (escape guide portion), 30 ... piston, 40, 140, 240 ... cushion portion 41, 141, 241 ... Cushion ring, 42, 242 ... Cushion passage, 45 ... Restriction pin (regulation part), 145 ... Restriction ring, 243 ... Central recess, 245 ... Expansion / contraction ring, 245A ... Joint gap, 246 ... Center stage Part, 51 ... contact part

Claims (10)

A cylinder tube;
A piston rod inserted into the cylinder tube;
A piston connected to the tip of the piston rod and dividing the cylinder tube into a rod side chamber and a bottom side chamber;
A cushion portion provided on the outer periphery of the piston rod for decelerating the piston rod in the vicinity of a stroke end during extension operation;
A supply / discharge passage through which the working fluid communicated with the rod side chamber passes through the rod side chamber;
A contact portion provided in the cylinder tube and in contact with the cushion portion near the stroke end at the time of extension operation;
The cushion portion is a cushion ring that contacts the contact portion in the vicinity of the stroke end during the extension operation, and a relative position of the cushion ring relative to the piston rod in a state of being accommodated in a recess formed on the outer peripheral surface of the piston rod. And a regulation unit that regulates movement,
As the cushion ring and the contact portion abut near the stroke end during the extension operation, direct communication between the supply / exhaust passage and the rod side chamber is blocked by the cushion ring and the restricting portion is The cushion ring is allowed to move relative to the piston rod by escaping from the recess, and the working fluid in the rod side chamber is discharged from the supply / discharge passage through a cushion passage that provides resistance to the working fluid passing therethrough. Fluid pressure cylinder. The inner peripheral surface of the cylinder tube has a sliding surface on which the piston slides, and a large-diameter surface formed with an inner diameter larger than the sliding surface,
2. The restricting portion is controlled to escape from the concave portion by contact with the sliding surface, and is allowed to escape from the concave portion by facing the large diameter surface. The fluid pressure cylinder described.   At least one of the restricting portion or the recessed portion is pushed out radially outwardly with the movement of the piston rod in the extending direction from the state where the cushion ring and the abutting portion are in contact with each other. The fluid pressure cylinder according to claim 1, wherein an escape guide portion for allowing escape from the concave portion is formed. The inner peripheral surface of the cylinder tube further includes an inner peripheral stepped portion formed between the sliding surface and a large diameter surface formed with an inner diameter larger than the sliding surface,
At least one of the restricting portion and the inner circumferential step portion is configured to move the restricting portion radially inward as the piston rod moves in a contracting direction from a state in which the cushion ring and the abutting portion abut. The fluid pressure cylinder according to claim 2 or 3, wherein an accommodation guide portion that is pushed out and accommodated in the concave portion is formed.   The axial gap is formed between the restricting portion and the inner circumferential step portion in a state where the cushion ring and the contact portion are in contact with each other. Fluid pressure cylinder.   The fluid pressure cylinder according to any one of claims 1 to 5, wherein the cushion passage is formed in an orifice plug that is detachably provided on the cushion ring.   The fluid according to any one of claims 1 to 6, wherein the restricting portion is a restricting pin that is inserted through an outer peripheral surface and an inner peripheral surface of the cushion ring and is movable in a radial direction. Pressure cylinder.   7. The fluid according to claim 1, wherein the restricting portions are a pair of restricting rings that are provided on an outer periphery and an inner periphery of the cushion ring, respectively, and are formed to be expandable and contractible. Pressure cylinder.   The said restriction | limiting part is an expansion / contraction ring provided adjacent to the said cushion ring in the axial direction, and having an abutment clearance gap so that expansion / contraction is possible. Fluid pressure cylinder. The cushion ring has a central recess formed on the inner side of the end surface facing the expansion / contraction ring,
The expansion / contraction ring has a central step portion inserted into the central recess,
In the state where the expansion / contraction ring is accommodated in the concave portion of the piston rod, a radial gap is formed between the central concave portion and the central step portion,
10. The fluid pressure cylinder according to claim 9, wherein the central step portion contacts the central concave portion when the expansion / contraction ring expands and escapes from the concave portion.

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