JP2013245734A - Hydraulic cylinder - Google Patents

Abstract

An object of the present invention is to reduce the moving speed of a piston when the piston moves close to the stroke end, and to prevent the piston from being pushed back immediately before reaching the stroke end.
During a stroke in which a piston (20) is moving toward the rod end (14), which is the stroke end side, a second pressure action chamber (162) is sealed, and the air pressure in the second pressure action chamber (162) increases. . Thereby, since the pressure of the air in the second pressure working chamber 162 becomes the back pressure against the piston 20, the piston 20 moves toward the stroke end while decelerating. Then, immediately before the piston 20 reaches the stroke end, the second pressure working chamber 162 and the second supply / discharge channel 32 communicate with each other via the second communication passage 42. For this reason, the air in the second pressure working chamber 162 is discharged to the second supply / discharge passage 32 via the second communication passage 42.
[Selection] Figure 1

Description

  The present invention relates to a fluid pressure cylinder.

  As this kind of thing, there exists a thing of patent document 1, for example. As shown in FIG. 7, a cylinder air chamber 102 (cylinder chamber) is formed in a cylinder tube 101 that forms the outline of the air cylinder 100 of Patent Document 1. An annular piston 103 is accommodated in the cylinder air chamber 102. A piston rod 104 is fixed to the piston 103. A cushion ring 105 is fixed on the opposite side of the piston 103 from the piston rod 104.

  The cylinder tube 101 has a piping port 106 for supplying and discharging air, a cushion air chamber 107 that communicates with the piping port 106 and opens to the cylinder air chamber 102, and a ventilation that communicates the cushion air chamber 107 and the cylinder air chamber 102. A hole 108 is formed. A cushion packing 109 is provided in an opening of the cushion air chamber 107 on the cylinder air chamber 102 side. A check valve 110 and a cushion valve 111 are disposed in the vent hole 108.

  The air in the cylinder air chamber 102 is discharged from the piping port 106 via the cushion air chamber 107 until the piston 103 moves toward the cushion air chamber 107 and immediately before the cushion ring 105 is fitted into the cushion packing 109. Is done. Then, the piston 103 further moves toward the cushion air chamber 107, and the cushion ring 105 is fitted into the cushion packing 109. Then, the flow of air flowing from the cylinder air chamber 102 into the cushion air chamber 107 is restricted, and the air in the cylinder air chamber 102 flows into the vent hole 108, passes through the gap of the cushion valve 111, and flows into the cushion air chamber 107. At that time, the check valve 110 closes the passage to the cushion air chamber 107 by the air flow. When the cushion valve 111 is in the throttled state, the air pressure in the cylinder air chamber 102 increases. Since the pressure of the air in the cylinder air chamber 102 becomes a back pressure against the piston 103, the piston 103 reaches the stroke end while decelerating. As a result, the impact when the piston 103 reaches the stroke end is reduced.

Japanese Utility Model Publication No. 6-51507

  As described above, in Patent Document 1, the cushion valve 111 is throttled to increase the air pressure in the cylinder air chamber 102 and to reduce the impact when reaching the stroke end of the piston 103. However, in order to reduce the size of the air cylinder 100, for example, the smaller the diameter of the cylinder air chamber 102, the smaller the volume of the cylinder air chamber 102 becomes. As the volume of the cylinder air chamber 102 decreases, even when the cushion valve 111 is throttled, the air pressure in the cylinder air chamber 102 does not function as a back pressure against the piston 103, and the piston 103 reaches the stroke end. It will not be possible to mitigate the impact.

  Therefore, the air pressure in the cylinder air chamber 102 is increased by closing the vent hole 108 and sealing the cylinder air chamber 102 so that the air in the cylinder air chamber 102 does not flow out to the vent hole 108. Can be considered. However, when this is done, air is not discharged from the cylinder air chamber 102 to the piping port 106 but is accumulated in the cylinder air chamber 102. As a result, there is a problem that the piston 103 is pushed back by the compression reaction force of the air accumulated in the cylinder air chamber 102.

  The present invention has been made in order to solve the above-described problem, and its purpose is to decelerate the moving speed of the piston when the piston moves to near the stroke end and immediately before the piston reaches the stroke end. An object of the present invention is to provide a fluid pressure cylinder capable of preventing being pushed back.

  In order to achieve the above object, according to the first aspect of the present invention, a cylinder chamber is formed in a cylinder tube, and a piston is accommodated in the cylinder chamber so as to be movable in an axial direction of the cylinder tube. Pressure working chambers are partitioned one by one across the piston in the cylinder chamber, and supply / exhaust flow passages for supplying and discharging fluid to and from each pressure working chamber are formed in the cylinder tube, respectively. In a fluid pressure cylinder provided with a piston rod that can be retracted and retracted with respect to a cylinder tube, the piston rod is at least one of a projecting direction and a retracting direction with respect to the cylinder tube, and is disposed on a stroke end side of the piston. The pressure action chamber located is the stroke end side pressure action chamber, and the stroke Assuming that the supply / exhaust flow path for supplying and discharging the fluid to the pressure side pressure working chamber is the stroke end side supply / exhaust flow path, the stroke end side supply / exhaust flow path is a stroke in which the piston moves toward the stroke end side. The stroke end side supply / exhaust flow path is formed at an intermediate position, and one end of the piston communicates with the stroke end side pressure acting chamber, and the other end immediately before the piston reaches the stroke end. A communication passage communicating with the stroke end side pressure working chamber is provided between the other end of the communication passage on the outer surface of the piston and the stroke end side pressure acting chamber from the stroke end side pressure acting chamber side. A first seal member for restricting the flow of fluid to the exhaust flow path side is provided, and further, the first seat on the outer surface of the piston is provided. Between the member and the other end of the communication passage, a second seal member is provided for sealing between the other end of the communication passage and the stroke end side supply / exhaust flow path in the middle of the stroke of the piston. The other end of the communication passage on the outer surface of the piston is located on the opposite side to the stroke end, and the other end of the communication passage is located on the opposite side of the stroke end side in the middle of the piston stroke. The gist of the invention is that a third seal member is provided for sealing between the supply / discharge flow path.

  According to a second aspect of the present invention, in the first aspect of the invention, the first seal member allows fluid to flow from the stroke end side supply / discharge flow path side to the stroke end side pressure acting chamber side. This is the gist.

  According to a third aspect of the present invention, in the second aspect of the present invention, the stroke end side supply / discharge flow path communicates with the other end of the communication passage immediately before the piston reaches the stroke end. A second communication path that communicates between the first seal member and the second seal member in the cylinder chamber when communication between the communication path and the other end of the communication path and the first communication path is interrupted The main point is that

  According to a fourth aspect of the present invention, in the second aspect of the present invention, the opening area on the cylinder chamber side in the stroke end side supply / discharge flow path is such that the second seal member is on the stroke end side supply / discharge flow path. The fluid flowing from the stroke end side supply / exhaust flow path when passing through the outside of the second seal member has an opening area that can flow toward the first seal member. The gist.

  The gist of the invention according to claim 5 is that, in the invention according to any one of claims 1 to 4, the second seal member and the third seal member are integrated.

  According to the present invention, it is possible to decelerate the moving speed of the piston when the piston moves close to the stroke end, and to prevent the piston from being pushed back immediately before reaching the stroke end.

Sectional drawing which shows the air cylinder in embodiment. Sectional drawing which shows the middle of the stroke which the piston is moving toward the stroke end side. Sectional drawing which shows the middle of the stroke which the piston is moving toward the stroke end side. Sectional drawing which shows the state which the piston reached | attained the stroke end. (A) And (b) is the elements on larger scale which show the air cylinder in another embodiment. The partial expanded sectional view which shows the air cylinder in another embodiment. Sectional drawing which shows the air cylinder in a prior art example.

Hereinafter, an embodiment in which the present invention is embodied in an air cylinder will be described with reference to FIGS.
As shown in FIG. 1, a through-hole 12 is formed in a cylinder tube 11 that forms the outline of the air cylinder 10. The through hole 12 extends along the axial direction of the cylinder tube 11. A head cover 13 is attached to one end (the right end in FIG. 1) of the through hole 12, and one end of the through hole 12 is closed by the head cover 13. A cylindrical rod cover 14 is attached to the other end of the through hole 12 (left end in FIG. 1). A rubber rod packing 15 is attached to the inner peripheral surface of the rod cover 14. A cylinder chamber 16 is defined in the through hole 12 by a space defined by the head cover 13 and the rod cover 14. The cylinder chamber 16 accommodates a piston 20 that is movable along the axial direction of the cylinder tube 11 by air as a fluid.

  The piston 20 divides the cylinder chamber 16 into a first pressure acting chamber 161 as a pressure acting chamber on the head cover 13 side and a second pressure acting chamber 162 as a pressure acting chamber on the rod cover 14 side. A piston rod 21 projects from a rod-side end surface 20a which is an end surface of the piston 20 on the rod cover 14 side. The piston rod 21 can pass in and out of the cylinder tube 11 through the inside of the rod cover 14.

  A first supply / discharge channel 31 serving as a supply / discharge channel for supplying / exhausting air to / from the first pressure acting chamber 161 is formed on the side of the head cover 13 at a position in the middle of the stroke of the piston 20 in the cylinder tube 11. Has been. Further, a second supply / exhaust flow path as a supply / discharge flow path for supplying / exhausting air to / from the second pressure acting chamber 162 on the rod cover 14 side at a position in the middle of the stroke of the piston 20 in the cylinder tube 11. 32 is formed.

  The first supply / discharge flow path 31 includes a first supply / discharge port 31a to which a pipe connection joint (not shown) is connected, a first flow path 31b communicating the first supply / discharge port 31a and the cylinder chamber 16, The first flow path 31b includes a second flow path 31c that opens to a position closer to the head cover 13 than the opening position on the cylinder chamber 16 side and communicates the first supply / discharge port 31a and the cylinder chamber 16. The second supply / discharge flow path 32 includes a second supply / discharge port 32a to which a pipe connection joint (not shown) is connected, a third flow path 32b communicating the second supply / discharge port 32a and the cylinder chamber 16; The third flow path 32b includes a fourth flow path 32c that opens to a position closer to the rod cover 14 than an opening position on the cylinder chamber 16 side and communicates the second supply / discharge port 32a and the cylinder chamber 16. .

  The piston 20 is formed with a first communication path 41 as a communication path including a first communication path 41a and a second communication path 41b. The first communication passage 41 a extends along the axial direction of the piston 20 from a head-side end surface 20 b that is an end surface of the piston 20 on the head cover 13 side. A first opening 411a that opens to the first pressure acting chamber 161 is formed at the end of the first communication passage 41a on the head cover 13 side. The first opening 411 a corresponds to one end of the first communication passage 41. The second communication passage 41b communicates with the end of the first communication passage 41a on the rod cover 14 side and extends in a direction orthogonal to the axial direction of the piston 20. A second opening 411b is formed at the end of the second communication passage 41b opposite to the first communication passage 41a. The second opening 411b corresponds to the other end of the first communication passage 41 and communicates with the first flow path 31b of the first supply / discharge flow path 31 immediately before the piston 20 reaches the scroll end on the head cover 13 side. It is formed in the position to do.

  The piston 20 is formed with a second communication path 42 as a communication path including a third communication path 42a, a fourth communication path 42b, and a fifth communication path 42c. The third communication passage 42 a extends from the head-side end surface 20 b of the piston 20 along the axial direction of the piston 20. A sealing member 43 is attached to the end of the third communication passage 42 a on the head cover 13 side, and communication between the first pressure action chamber 161 and the third communication passage 42 a is restricted by the sealing member 43. The fourth communication passage 42 b communicates in the middle of the third communication passage 42 a and extends in a direction orthogonal to the axial direction of the piston 20. A third opening 421b is formed at the end of the fourth communication passage 42b opposite to the third communication passage 42a. The third opening 421b corresponds to the other end of the second communication passage 42, and is provided in the third flow path 32b of the second supply / discharge flow path 32 immediately before the piston 20 reaches the scroll end on the rod cover 14 side. It is formed in a communicating position. The fifth communication passage 42c communicates with the end of the third communication passage 42a on the rod cover 14 side and extends in a direction orthogonal to the axial direction of the piston 20. A fourth opening 421c that opens to the second pressure action chamber 162 is formed at the end of the fifth communication passage 42c opposite to the third communication passage 42a. The fourth opening 421 c corresponds to one end of the second communication passage 42.

  An annular first lip packing 51 is mounted between the second opening 411 b and the first pressure acting chamber 161 on the outer peripheral surface (outer surface) of the piston 20. The first lip packing 51 allows air to flow from the first supply / exhaust flow path 31 side to the first pressure action chamber 161 side, and from the first pressure action chamber 161 side to the first supply / discharge flow path 31 side. Regulates air flow.

  In addition, an annular first squeeze packing 52 that seals between the outer peripheral surface of the piston 20 and the cylinder chamber 16 is mounted between the first lip packing 51 and the second opening 411 b on the outer peripheral surface of the piston 20. Has been. Further, an annular second squeeze packing 53 for sealing between the outer peripheral surface of the piston 20 and the cylinder chamber 16 is mounted between the second opening 411b and the third opening 421b on the outer peripheral surface of the piston 20. Has been.

  An annular second lip packing 54 is mounted between the third opening 421 b and the second pressure acting chamber 162 on the outer peripheral surface of the piston 20. The second lip packing 54 allows air to flow from the second supply / exhaust flow path 32 side to the second pressure action chamber 162 side, and from the second pressure action chamber 162 side to the second supply / discharge flow path 32 side. Regulates air flow. In addition, an annular third squeeze packing 55 that seals between the outer peripheral surface of the piston 20 and the cylinder chamber 16 is mounted between the second lip packing 54 and the third opening 421 b on the outer peripheral surface of the piston 20. Has been.

Next, the operation of the air cylinder 10 configured as described above will be described.
In a state where the piston rod 21 is immersed in the cylinder tube 11, first, air is supplied from the supply source to the first flow path 31 b and the second flow path 31 c of the first supply / discharge flow path 31. The air supplied to the first flow path 31b flows into the first pressure working chamber 161 from the first opening 411a via the second communication path 41b and the first communication path 41a via the second opening 411b. In addition, the air supplied to the second flow path 31 c is supplied to the cylinder chamber 16 and passes between the first lip packing 51 and the inner peripheral surface of the cylinder tube 11 to enter the first pressure working chamber 161. Flows in. Then, the piston 20 is pressed by the air flowing into the first pressure working chamber 161 and moves toward the rod cover 14, and the piston rod 21 protrudes from the cylinder tube 11 (protrusion direction of the piston rod 21). Move to. At this time, the air in the second pressure action chamber 162 corresponding to the stroke end side pressure action chamber located on the stroke end side of the piston 20 is discharged from the second supply / discharge flow path 32 corresponding to the stroke end side supply / discharge flow path. Is done.

  When the piston 20 moves toward the rod cover 14, the communication between the first flow path 31b and the second opening 411b is cut off, so that the first opening is made via the second communication path 41b and the first communication path 41a. The flow of air flowing from the portion 411a into the first pressure action chamber 161 is blocked. However, since the second flow path 31c communicates between the first lip packing 51 and the first squeeze packing 52 in the cylinder chamber 16, the air supplied from the second flow path 31c to the cylinder chamber 16 is The first lip packing 51 and the inner peripheral surface of the cylinder tube 11 pass between the first lip packing 51 and the first pressure working chamber 161. Therefore, the second flow path 31c communicates between the first lip packing 51 and the first squeeze packing 52 in the cylinder chamber 16 when the communication between the first flow path 31b and the second opening 411b is blocked. This corresponds to the second communication path. Then, as shown in FIG. 2, the piston 20 is further pressed toward the rod cover 14 by being pressed by the air that has flowed into the first pressure working chamber 161.

  As shown in FIG. 3, when the piston 20 moves toward the rod cover 14 until the second lip packing 54 passes over the third flow path 32b and the fourth flow path 32c, the second pressure working chamber is moved by the second lip packing 54. 162 air is restricted from being discharged from the second supply / discharge flow path 32. That is, the second lip packing 54 allows air to flow from the second supply / exhaust flow path 32 side to the second pressure action chamber 162 side, and from the second pressure action chamber 162 side to the second supply / discharge flow path 32. This corresponds to a first seal member that regulates the air flow to the side.

  Further, the second pressure working chamber 162 passes through the fourth opening 421c, the fifth communication passage 42c, the third communication passage 42a, and the fourth communication passage 42b, and then passes from the third opening 421b to the second supply / discharge passage. The third squeeze packing 55 restricts the flow of air that is about to flow toward the position 32. Therefore, the third squeeze packing 55 functions as a second seal member that seals between the third opening 421b and the second supply / discharge channel 32 during the stroke of the piston 20. Further, the second pressure working chamber 162 passes through the fourth opening 421c, the fifth communication passage 42c, the third communication passage 42a, and the fourth communication passage 42b, and then passes through the third opening 421b to the first supply / discharge passage. The flow of air that tends to flow toward the side 31 is regulated by the second squeeze packing 53. Therefore, the second squeeze packing 53 functions as a third seal member that seals between the third opening 421b and the first supply / discharge channel 31 during the stroke of the piston 20. Thereby, the second pressure working chamber 162 is sealed, the pressure of the air in the second pressure working chamber 162 is increased, and the pressure of the air in the second pressure working chamber 162 becomes a back pressure against the piston 20. As a result, the piston 20 moves toward the rod cover 14 while decelerating. In addition, in order to press the piston 20 toward the rod cover 14 side, the pressure of the air supplied to the first pressure action chamber 161 is larger than the pressure of the air in the second pressure action chamber 162.

  The third opening 421b and the third flow path 32b communicate with each other immediately before the piston 20 reaches the end surface 14e of the rod cover 14 that is the stroke end while decelerating. Therefore, the third flow path 32b corresponds to the first communication path. As a result, the air in the second pressure working chamber 162 passes through the fourth opening 421c, passes through the fifth communication passage 42c, the third communication passage 42a, and the fourth communication passage 42b, and passes through the third opening 421b. It is discharged to the flow path 32b. Therefore, air does not accumulate in the second pressure working chamber 162, and the piston 20 is not pushed back to the head cover 13 side by the compression reaction force of the air in the second pressure working chamber 162. As a result, as shown in FIG. 4, the piston 20 reaches the end surface 14e of the rod cover 14 while decelerating, and the movement of the piston 20 toward the rod cover 14 is stopped.

  In the present embodiment, the distance from the rod side end surface 20a of the piston 20 to the end surface 14e of the rod cover 14 when the second lip packing 54 gets over the fourth flow path 32c reduces the moving speed of the piston 20. The desired cushion stroke length is required. The cushion stroke length can be adjusted by the position where the fourth flow path 32 c is formed and the position where the second lip packing 54 is disposed.

  In a state where the piston rod 21 protrudes from the cylinder tube 11, air is supplied from the supply source to the third flow path 32 b and the fourth flow path 32 c of the second supply / discharge flow path 32. The air supplied to the third flow path 32b is supplied from the fourth opening 421c through the third opening 421b to the second pressure via the fourth communication path 42b, the third communication path 42a, and the fifth communication path 42c. It flows into the working chamber 162. The air supplied to the fourth flow path 32 c is supplied to the cylinder chamber 16 and passes between the second lip packing 54 and the inner peripheral surface of the cylinder tube 11 to enter the second pressure working chamber 162. Flows in. Then, the piston 20 is pressed and moved toward the head cover 13 by the air flowing into the second pressure acting chamber 162, and the piston rod 21 is immersed in the cylinder tube 11 (in the direction in which the piston rod 21 is immersed). Moving. At this time, the air in the first pressure action chamber 161 corresponding to the stroke end side pressure action chamber located on the stroke end side of the piston 20 is discharged from the first supply / discharge flow path 31 corresponding to the stroke end side supply / discharge flow path. Is done.

  When the piston 20 moves toward the head cover 13, the communication between the third flow path 32b and the third opening 421b is cut off, so that the fourth communication path 42b, the third communication path 42a, and the fifth communication path 42c are routed. Thus, the flow of air flowing from the fourth opening 421c into the second pressure working chamber 162 is blocked. However, since the fourth flow path 32c communicates between the second lip packing 54 and the third squeeze packing 55 in the cylinder chamber 16, the air supplied from the fourth flow path 32c to the cylinder chamber 16 does not flow. The second lip packing 54 and the inner peripheral surface of the cylinder tube 11 pass between the second lip packing 54 and the second pressure working chamber 162. Therefore, the fourth flow path 32c communicates between the second lip packing 54 and the third squeeze packing 55 in the cylinder chamber 16 when the communication between the third flow path 32b and the third opening 421b is blocked. This corresponds to the second communication path. As shown in FIG. 3, the piston 20 is further pressed toward the head cover 13 by being pressed by the air flowing into the second pressure acting chamber 162.

  As shown in FIG. 2, when the piston 20 moves toward the head cover 13 until the first lip packing 51 passes over the first flow path 31b and the second flow path 31c, the first pressure working chamber 161 is moved by the first lip packing 51. The air is restricted from being discharged from the first supply / discharge channel 31. That is, the first lip packing 51 allows air to flow from the first supply / discharge flow path 31 side to the first pressure working chamber 161 side, and from the first pressure work chamber 161 side to the first supply / discharge flow path 31. This corresponds to a first seal member that regulates the air flow to the side.

  Further, the flow from the first pressure working chamber 161 to the first supply / discharge channel 31 through the first communication passage 41a and the second communication passage 41b through the first opening 411a and the first communication passage 41a. The air flow is regulated by the first squeeze packing 52. Therefore, the first squeeze packing 52 functions as a second seal member that seals between the second opening 411 b and the first supply / discharge channel 31 during the stroke of the piston 20. Furthermore, it flows from the first pressure working chamber 161 to the second supply / discharge flow path 32 side through the first communication passage 41a and the second communication passage 41b through the first opening 411a. The air flow is restricted by the second squeeze packing 53. Therefore, the second squeeze packing 53 functions as a third seal member that seals between the second opening 411b and the second supply / exhaust flow path 32 during the stroke of the piston 20. As a result, the first pressure working chamber 161 is sealed, the pressure of the air in the first pressure working chamber 161 increases, and the pressure of the air in the first pressure working chamber 161 becomes a back pressure against the piston 20. As a result, the piston 20 moves toward the head cover 13 while decelerating. In order to press the piston 20 toward the head cover 13 side, the pressure of the air supplied to the second pressure action chamber 162 is larger than the pressure of the air in the first pressure action chamber 161.

  The second opening 411b and the first flow path 31b communicate with each other immediately before the piston 20 reaches the end surface 13e of the head cover 13 that is the stroke end while decelerating. Therefore, the first flow path 31b corresponds to the first communication path. As a result, the air in the first pressure working chamber 161 is discharged from the second opening 411b to the first flow path 31b via the first opening 411a and the first communication passage 41a and the second communication passage 41b. The Therefore, air does not accumulate in the first pressure working chamber 161, and the piston 20 is not pushed back to the rod cover 14 side by the compression reaction force of the air in the first pressure working chamber 161. As a result, as shown in FIG. 1, the piston 20 reaches the end surface 13e of the head cover 13 while decelerating, and the movement of the piston 20 toward the head cover 13 is stopped.

  In the present embodiment, the distance from the head-side end surface 20b of the piston 20 to the end surface 13e of the head cover 13 when the first lip packing 51 gets over the second flow path 31c is necessary to reduce the moving speed of the piston 20. The desired cushion stroke length is obtained. The cushion stroke length can be adjusted by the position where the second flow path 31 c is formed and the position where the first lip packing 51 is disposed.

In the above embodiment, the following effects can be obtained.
(1) The first supply / discharge flow path 31 and the second supply / discharge flow path 32 are formed in the cylinder tube 11 at a position in the middle of the stroke of the piston 20. Further, one end of the piston 20 communicates with the first pressure working chamber 161 or the second pressure working chamber 162, and the other end immediately before the piston 20 reaches the stroke end, the first supply / discharge passage 31 or the second supply passage. A first communication path 41 or a second communication path 42 communicating with the exhaust flow path 32 was formed. Further, the first lip packing 51 or the second lip packing 54 is provided between the second opening 411 b or the third opening 421 b on the outer peripheral surface of the piston 20 and the first pressure action chamber 161 or the second pressure action chamber 162. It was. Further, the first squeeze packing 52 or the third squeeze packing 55 is provided between the first lip packing 51 or the second lip packing 54 and the second opening 411 b or the third opening 421 b on the outer peripheral surface of the piston 20. . Furthermore, the 2nd squeeze packing 53 was provided in the other side to the stroke end rather than the 2nd opening part 411b or the 3rd opening part 421b in the outer peripheral surface of the piston 20.

  According to this, during the stroke in which the piston 20 is moving toward the head cover 13 or the rod cover 14 on the stroke end side, the first pressure action chamber 161 or the second pressure action chamber 162 is sealed, and the first pressure action chamber 162 is sealed. The pressure of the air in the first pressure working chamber 161 or the second pressure working chamber 162 is increased. As a result, the pressure of the air in the first pressure working chamber 161 or the second pressure working chamber 162 becomes a back pressure against the piston 20, and the piston 20 moves toward the stroke end while decelerating. Then, immediately before the piston 20 reaches the stroke end, the first pressure action chamber 161 or the second pressure action chamber 162 and the first supply / discharge flow path 31 or the second supply / discharge flow path 32 are connected to the first communication path. 41 or the second communication passage 42. For this reason, the air in the first pressure working chamber 161 or the second pressure working chamber 162 flows into the first supply / discharge flow path 31 or the second supply / discharge flow path 32 via the first communication passage 41 or the second communication passage 42. Discharged. Therefore, the air in the first pressure action chamber 161 or the second pressure action chamber 162 is not discharged into the first supply / discharge flow path 31 or the second supply / discharge flow path 32, and the first pressure action chamber 161 or the second pressure action Air does not accumulate in the chamber 162. As a result, it is possible to prevent the air from accumulating in the first pressure working chamber 161 or the second pressure working chamber 162 and being pushed back immediately before the piston 20 reaches the stroke end due to the compression reaction force of the air. .

  (2) When the piston 20 starts moving toward the rod cover 14 or the head cover 13 after the piston 20 reaches the head cover 13 or the rod cover 14 that is the stroke end side, the first supply / discharge channel 31 or the second supply channel 31 Communication between the exhaust flow path 32 and the first communication path 41 or the second communication path 42 is blocked. However, the air supplied from the first supply / discharge flow path 31 or the second supply / discharge flow path 32 passes between the first lip packing 51 or the second lip packing 54 and the cylinder tube 11 and passes through the first pressure. It is allowed to flow toward the working chamber 161 or the second pressure working chamber 162 side. For this reason, the air supplied from the first supply / discharge flow path 31 or the second supply / discharge flow path 32 is supplied to the first pressure action chamber 161 or the second pressure action chamber 162, and the first pressure action chamber 161 or the second pressure action chamber 162. The piston 20 can be moved to the rod cover 14 or the head cover 13 side by the pressure of the air supplied to the two-pressure working chamber 162.

  (3) The piston 20 starts to move toward the rod cover 14 or the head cover 13, and the first supply / discharge flow path 31 or the second supply / discharge flow path 32 communicates with the first communication path 41 or the second communication path 42. Is cut off. However, the second flow path 31 c or the fourth flow path 32 c is between the first lip packing 51 and the first squeeze packing 52 or between the second lip packing 54 and the third squeeze packing 55 in the cylinder chamber 16. Communicating with Therefore, the air supplied to the cylinder chamber 16 from the second flow path 31c or the fourth flow path 32c is allowed to pass between the first lip packing 51 or the second lip packing 54 and the inner peripheral surface of the cylinder tube 11. Thus, the first pressure working chamber 161 or the second pressure working chamber 162 can be supplied.

  (4) According to the present embodiment, the speed of the piston 20 toward the stroke end is reduced by sealing the first pressure action chamber 161 or the second pressure action chamber 162. Therefore, for example, even if the diameter of the cylinder chamber 16 is reduced, the air in the first pressure acting chamber 161 or the second pressure acting chamber 162 can function as a back pressure, and the air cylinder 10 can be reduced in size. Is possible.

In addition, you may change the said embodiment as follows.
In the embodiment, the second flow path 31c may be deleted. And as shown to Fig.5 (a), you may form the taper part 311b which diameter-expands, for example at the opening edge of the 1st flow path 31b toward the opening end of the 1st flow path 31b. By forming the tapered portion 311b, the opening area of the first flow path 31b is such that even if the first squeeze packing 52 is positioned on the first flow path 31b, the air flowing from the first flow path 31b is the first squeeze. It is sealed by the packing 52, and has an opening area where it cannot flow into the first pressure acting chamber 161 side. That is, as shown in FIG. 5 (b), even if the piston 20 moves and the first squeeze packing 52 is positioned on the first flow path 31b, the air from the first flow path 31b remains in the first squeeze. Without being sealed by the packing 52, it can pass through the outside of the first squeeze packing 52 and flow into the first lip packing 51 (first pressure working chamber 161) side. Therefore, even if the piston 20 moves and the communication between the first flow path 31b and the first communication path 41 is blocked, the air in the first flow path 31b flows toward the first pressure action chamber 161 side. Air can be supplied to the first pressure working chamber 161. Similarly, the fourth flow path 32c may be deleted, and a tapered portion whose diameter increases toward the opening end of the third flow path 32b may be formed at the opening edge of the third flow path 32b. In addition, even if the first squeeze packing 52 is positioned on the first flow path 31b without forming the taper portion 311b, the air flowing from the first flow path 31b is the first flow path 31b. It is good also as a flow-path area which is sealed by 1 squeeze packing 52 and cannot flow into the 1st pressure action chamber 161 side.

  As shown in FIG. 6, a squeeze packing 61 in which the first to third squeeze packings 52, 53, and 55 are integrated may be attached to the outer peripheral surface of the piston 20. In the squeeze packing 61, a communication hole 61 a that forms a part of the first communication path 41 and a communication hole 61 b that forms a part of the second communication path 42 are formed. According to this, it is not necessary to form three grooves for mounting the first to third squeeze packings 52, 53, 55 in the piston 20, and one groove for mounting the squeeze packing 61 is formed. Therefore, the processing of the piston 20 can be simplified. Moreover, in the groove | channel where the 1st-3rd squeeze packing 52, 53, 55 is mounted | worn, the length of the axial direction in piston 20 can be shortened by the part which exists between adjacent grooves.

  In the embodiment, a speed controller is disposed in the first supply / discharge flow path 31 and the second supply / discharge flow path 32, and air is supplied / discharged to the first supply / discharge flow path 31 and the second supply / discharge flow path 32. The flow rate may be adjusted. According to this, it becomes possible to adjust the moving speed of the piston 20.

  In the embodiment, the piston 20 may reach the stroke end while decelerating the moving speed of the piston 20 only in the projecting direction of the piston rod 21, or the piston 20 only in the immersion direction of the piston rod 21. The piston 20 may reach the stroke end while decelerating the movement speed. For example, when the moving speed of the piston 20 is decelerated only in the projecting direction of the piston rod 21, the first communication passage 41, the first lip packing 51, and the first squeeze packing 52 may be deleted. The first supply / discharge channel is formed in the cylinder tube 11 so as to be close to the head cover 13. Further, for example, when the moving speed of the piston 20 is reduced only in the direction in which the piston rod 21 is immersed, the second communication passage 42, the second lip packing 54, and the third squeeze packing 55 may be deleted. Then, the second supply / discharge channel is formed in the cylinder tube 11 so as to be close to the rod cover 14.

  In the embodiment, the piston 20 may be moved using a fluid other than air.

  DESCRIPTION OF SYMBOLS 10 ... Air cylinder as fluid pressure cylinder, 11 ... Cylinder tube, 16 ... Cylinder chamber, 20 ... Piston, 21 ... Piston rod, 31 ... 1st supply / discharge flow path as supply / discharge flow path, 31b ... 1st communicating path A second flow path corresponding to the second communication path, 32 a second supply / discharge flow path as the supply / discharge flow path, 32b a third flow path corresponding to the first communication path 32c, a fourth flow path corresponding to the second communication path, 41, a first communication path as the communication path, 42, a second communication path as the communication path, 51, a first lip packing that functions as a first seal member 52 ... First squeeze packing that functions as a second seal member, 53 ... Second squeeze packing that functions as a third seal member, 54 ... Second lip packing corresponding to the first seal member, 55 ... As a second seal member Machine Third squeeze packing, 161 ... first pressure working chamber as a pressure working chamber, 162 ... second pressure working chamber as a pressure working chamber to.

Claims (5)

A cylinder chamber is formed in the cylinder tube, and a piston is accommodated in the cylinder chamber so as to be movable in an axial direction of the cylinder tube, and the pressure action chamber is partitioned one by one with the piston in between in the cylinder chamber. The cylinder tube is formed with a supply / exhaust flow path for supplying and discharging fluid to and from each pressure working chamber, and the piston is provided with a piston rod that can be moved into and out of the cylinder tube. In the cylinder,
The pressure action chamber located at the stroke end side of the piston in at least one of the projecting direction and the immersion direction of the piston rod with respect to the cylinder tube is defined as the stroke end side pressure action chamber, and the stroke end side pressure action If the supply / discharge flow path for supplying and discharging fluid to / from the chamber is a stroke end side supply / discharge flow path, the stroke end side supply / discharge flow path is at a position in the middle of the stroke where the piston is moving toward the stroke end side. Formed,
One end of the piston communicates with the stroke end side pressure working chamber, and the other end of the piston communicates with the stroke end side supply / exhaust flow channel immediately before the piston reaches the stroke end. And
Between the other end of the communication passage on the outer surface of the piston and the stroke end side pressure action chamber, the flow of fluid from the stroke end side pressure action chamber side to the stroke end side supply / discharge flow path side is regulated. A first seal member is provided;
Further, between the first seal member on the outer surface of the piston and the other end of the communication passage, between the other end of the communication passage and the stroke end side supply / discharge passage in the middle of the stroke of the piston. A second seal member is provided to seal the other end of the communication passage on the outer surface of the piston opposite to the stroke end from the other end of the communication passage. A fluid pressure cylinder is provided with a third seal member for sealing between the supply / discharge flow path located on the side opposite to the stroke end side.   2. The fluid pressure cylinder according to claim 1, wherein the first seal member allows fluid to flow from the stroke end side supply / discharge flow path side to the stroke end side pressure acting chamber side. 3.   The stroke end side supply / discharge flow path includes a first communication path that communicates with the other end of the communication path immediately before the piston reaches the stroke end, and the other end of the communication path and the first communication path. 3. The fluid according to claim 2, further comprising: a second communication passage communicating between the first seal member and the second seal member in the cylinder chamber when communication is blocked. Pressure cylinder.   The opening area on the cylinder chamber side in the stroke end side supply / discharge flow path is such that the fluid flowing from the stroke end side supply / discharge flow path when the second seal member is positioned on the stroke end side supply / discharge flow path. 3. The fluid pressure cylinder according to claim 2, wherein the fluid pressure cylinder has an opening area capable of passing through the outside of the second seal member and flowing toward the first seal member.   The fluid pressure cylinder according to any one of claims 1 to 4, wherein the second seal member and the third seal member are integrated.