Cylinder

Abstract

In the buffer mechanism of the cylinders (10A to 10C), when the pressure of the gas in the first pressure chamber is equal to or lower than a specified pressure, the valve element (84) cuts off the communication between the upstream side and the downstream side of the discharge flow path (82) due to the acting force of the spring member (86). Further, when the pressure of the gas exceeds the specified pressure, the valve element (84) displaces toward the downstream side of the discharge flow path (82) against the acting force, thereby connecting the upstream side and the downstream side of the discharge flow path (82).

Description

Technical Field

[0001] The present invention relates to a cylinder having a buffer mechanism for braking the movement of a piston when the piston stops at a stroke end. Background Art

[0002] Conventionally, for example, the following techniques are disclosed in Japanese Utility Model Laid-Open Publication No. 61-141804, Japanese Utility Model Laid-Open Publication No. 63-8405, Japanese Patent Laid-Open Publication No. 6-341411, and Japanese Patent No. 3466121: In a cylinder, a buffer mechanism is provided to mitigate the impact of a piston at a stroke end. These documents disclose that by internally providing a throttle valve in a cylinder cover and manually adjusting the opening degree of the throttle valve in accordance with the usage conditions of the cylinder such as the speed of the piston (cylinder speed), the discharge amount of the gas discharged from a pressure chamber (buffer chamber) between the stroke end and the piston via the throttle valve is adjusted.

[0003] However, in the case of dealing with a production facility provided with a plurality of cylinders having the same structure, it is necessary to manually adjust the throttle valves of each cylinder, so the burden on the person in charge becomes large.

[0004] In addition, the manual adjustment of the throttle valve depends on the feel of the person in charge. And since the opening degree of the throttle valve is manually adjusted by a threaded adjustment mechanism, it is necessary to perform daily maintenance such as confirming the presence or absence of loosening of the screw caused by vibration of the production facility or the like. As a result, manual adjustment needs to be repeated.

[0005] Moreover, since it is necessary to internally provide a throttle valve in a limited space inside the cover, it is impossible to increase the cross-sectional area of the gas flow path.

[0006] In addition, in the case where the cylinder speed is a high-speed specification, by manually adjusting the opening degree of the throttle valve to reduce the discharge amount of the gas, the cylinder speed at the stroke end side can be decelerated. As a result, the pressure in the buffer chamber is higher than the pressure on the pressurizing chamber side, and a bounce phenomenon occurs in which the piston is pushed back in the direction opposite to the traveling direction. As a result, the production cycle time becomes long, and losses of the production facility occur. Summary of the Invention

[0007] The present invention has been made in consideration of such technical problems, and an object thereof is to provide a cylinder that does not require manual adjustment, can suppress the occurrence of the bounce phenomenon, and can achieve smooth arrival of the piston at the stroke end and mitigation of the impact on the piston.

[0008] The method of the present invention relates to a cylinder, comprising: a cylinder barrel in which a cylinder chamber is formed inside; a first cover that seals one end of the cylinder barrel; a second cover that seals the other end of the cylinder barrel; a piston that divides the cylinder chamber into a first pressure chamber on the first cover side and a second pressure chamber on the second cover side, and the piston slides in the cylinder chamber; a piston rod that is connected to the piston; a first port that supplies gas to the first pressure chamber and discharges gas from the first pressure chamber; a second port that supplies gas to the second pressure chamber and discharges gas from the second pressure chamber; and a buffer mechanism that brakes the movement of the piston at least when the piston stops at the stroke end on the first cover side.

[0009] The buffer mechanism has: a communication cut-off part that cuts off the communication state between the first pressure chamber and the first port when the piston approaches the stroke end; a throttle hole part that is provided on the first cover and discharges the gas in the first pressure chamber; and a discharge flow rate adjustment part that is provided on the first cover and, when the pressure in the first pressure chamber exceeds a specified pressure, the discharge flow rate adjustment part acts together with the throttle hole part to discharge gas from the first pressure chamber.

[0010] The discharge flow rate adjustment part is formed inside the first cover and has: a discharge flow path for discharging the gas in the first pressure chamber; a spool valve type spool that is disposed in the middle of the discharge flow path; and an elastic body that applies a force to the spool toward the upstream side of the discharge flow path.

[0011] Moreover, when the pressure is below the specified pressure, the spool cuts off the communication state between the upstream side and the downstream side of the discharge flow path due to the acting force of the elastic body. In addition, when the pressure exceeds the specified pressure, the spool is displaced toward the downstream side of the discharge flow path due to the pressure, thereby overcoming the acting force, and thus the upstream side and the downstream side of the discharge flow path are communicated.

[0012] According to the present invention, when the pressure in the first pressure chamber (buffer chamber) is below the specified pressure, the spool cuts off the communication state between the upstream side and the downstream side of the discharge flow path due to the acting force from the elastic body, so the gas in the buffer chamber is discharged only through the throttle hole part. In addition, when the pressure in the first pressure chamber exceeds the specified pressure, the spool is displaced due to the pressure, overcoming the acting force, and the upstream side and the downstream side of the discharge flow path are communicated, so the gas in the first pressure chamber is discharged through the throttle hole part and also through the discharge flow path.

[0013] In this way, when the pressure exceeds the specified pressure, two paths are used to discharge the gas in the first pressure chamber. As a result, the gas in the first pressure chamber is discharged in a short time, so that the piston can reach the stroke end quickly and smoothly. As a result, the generation of the bounce phenomenon can be avoided, and the responsiveness of the cylinder can be improved.

[0014] In addition, by using the balance between the acting force of the elastic body and the pressure in the first pressure chamber to displace the spool valve, the upstream side and the downstream side of the discharge flow path are switched to the connected state or the cut-off state. Thus, manual adjustment of the spool valve is not required. That is, since it is a spool valve type spool, when the upstream side and the downstream side of the discharge flow path are in the connected state, the opening degree of the spool can be gradually changed according to the magnitude of the pressure in the first pressure chamber.

[0015] Therefore, in the present invention, manual adjustment of the spool valve is not required, the generation of the bounce phenomenon can be suppressed, and smooth arrival of the piston at the stroke end and mitigation of the impact on the piston can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a perspective view of the cylinder of the first embodiment.

[0017] Figure 2 is along Figure 1 sectional view taken along line II-II.

[0018] Figure 3A is Figure 1 partial top view of the rod cover periphery of the cylinder of Figure 3B is along Figure 3A main part sectional view taken along line IIIB-IIIB.

[0019] Figure 4A is a side view of the spool valve, Figure 4B is a top view of the spool valve.

[0020] Figure 5A and Figure 5B is a diagram showing Figure 1 main part sectional view of the operation of the cylinder of

[0021] Figure 6 is a diagram showing Figure 1 main part sectional view of the operation of the cylinder of

[0022] Figure 7 is a diagram showing Figure 1 timing diagram of the operation of the cylinder of

[0023] Figure 8 is a perspective view of the cylinder of the second embodiment.

[0024] Figure 9A isFigure 8 Partial top view of the periphery of the rod cover of the cylinder Figure 9B is a main part sectional view along the Figure 9A IXB-IXB line of

[0025] Figure 10 is a main part sectional view showing the operation of the Figure 8 cylinder

[0026] Figure 11A is a top view of the cover part of the cylinder of the third embodiment Figure 11B is a main part sectional view showing the operation of the cylinder Detailed implementation mode

[0027] Hereinafter, preferred embodiments of the cylinder of the present invention will be exemplified and described with reference to the drawings

[0028] [1. First embodiment]

[0029] <1.1 Structure of the first embodiment>

[0030] As shown in Figure 1 , the cylinder 10A of the first embodiment includes: a cylindrical cylinder barrel 12, a head cover 14 that seals (blocks) one end of the cylinder barrel 12, and a rod cover 16 that seals (blocks) the other end of the cylinder barrel 12. The cylinder barrel 12, the head cover 14, and the rod cover 16 are connected in the axial direction of the cylinder 10A by a plurality of connecting rods 18 and connecting bolts 20. A head-side port 22 is formed on the upper surface (one side) of the head cover 14. A rod-side port 24 is formed on the upper surface (the other side) of the rod cover 16. The piston rod 26 projects and extends from the rod cover 16. In addition, the axial direction of the cylinder 10A refers to the direction in which the piston rod 26 extends

[0031] As shown in Figure 2 , a cylinder chamber 28 is formed inside the cylinder barrel 12. A piston 30 is disposed in the cylinder chamber 28, and the piston 30 slides axially between the stroke start end (stroke end) on the head cover 14 side and the stroke end (stroke end) on the rod cover 16 side. The piston 30 divides the cylinder chamber 28 into a head-side pressure chamber 32 on the head cover 14 side and a rod-side pressure chamber 34 on the rod cover 16 side (see Figure 2 and Figure 5A )

[0032] The piston rod 26 is connected to the piston 30. One end of the piston rod 26 is connected to the piston 30. The other end of the piston rod 26 penetrates the rod cover 16 and projects to the outside. The head-side buffer pin 36 is connected to the head cover 14 side of the piston 30. On the rod cover 16 side of the piston 30, the rod-side buffer pin 38 is mounted on the outer peripheral surface of the piston rod 26

[0033] A recess-shaped head cover chamber 40 into which the head-side buffer pin 36 is inserted when the piston 30 approaches the start end of the approach stroke is formed in the head cover 14. A through hole 42 that penetrates upward into the head cover 14 is formed inside the head cover chamber 40. The head-side port 22 is formed through the through hole 42. Therefore, the head-side port 22 supplies gas to the head-side pressure chamber 32 and discharges gas from the head-side pressure chamber 32 via the head cover chamber 40. A buffer gasket 44 such as an O-ring that slidably contacts the head-side buffer pin 36 inserted into the head cover chamber 40 is provided on the piston 30 side of the head cover chamber 40.

[0034] A recess-shaped rod cover chamber 46 into which the rod-side buffer pin 38 is inserted when the piston 30 approaches the end of the approach stroke is formed in the rod cover 16. A through hole 48 that penetrates upward into the rod cover 16 is formed inside the rod cover chamber 46. The rod-side port 24 is formed through the through hole 48. Therefore, the rod-side port 24 supplies gas to the rod-side pressure chamber 34 and discharges gas from the rod-side pressure chamber 34 via the rod cover chamber 46. A buffer gasket 50 such as an O-ring that slidably contacts the rod-side buffer pin 38 inserted into the rod cover chamber 46 is provided on the piston 30 side of the rod cover chamber 46.

[0035] In addition, the gas supplied to the head-side pressure chamber 32 and the rod-side pressure chamber 34 and the gas discharged from the head-side pressure chamber 32 and the rod-side pressure chamber 34 is, for example, air. Therefore, the cylinder 10A of the first embodiment is applicable to, for example, an air cylinder.

[0036] A head-side buffer mechanism 52 is provided on the head cover 14 side of the cylinder 10A, and the head-side buffer mechanism 52 brakes the movement of the piston 30 when the piston 30 stops at the start end of the stroke. In addition, a rod-side buffer mechanism 54 is provided on the rod cover 16 side of the cylinder 10A, and the rod-side buffer mechanism 54 brakes the movement of the piston 30 when the piston 30 stops at the end of the stroke.

[0037] In addition, in the cylinder 10A, the buffer mechanism may be provided on at least one of the head cover 14 side and the rod cover 16 side. Further, when the piston 30 stops at the end of the stroke (start end of the stroke or end of the stroke), the space (head-side pressure chamber 32 or rod-side pressure chamber 34) between the piston 30 and the end of the stroke becomes a buffer chamber.

[0038] The head-side buffer mechanism 52 includes: a communication cut-off portion 56 that cuts off the communication state between the head-side pressure chamber 32 and the head-side port 22 when the piston 30 approaches the start end of the stroke; a throttle hole portion 58 that is provided in the head cover 14 and discharges the gas in the head-side pressure chamber 32; and a discharge flow rate adjustment portion 60 that is provided in the head cover 14 and, when the pressure in the head-side pressure chamber 32 exceeds a specified pressure, the discharge flow rate adjustment portion 60 cooperates with the throttle hole portion 58 to discharge gas from the head-side pressure chamber 32 (see Figure 1 、Figure 3A and Figure 3B )。As Figures 1 to 3B shown, the throttle orifice portion 58 and the discharge flow rate adjustment portion 60 are disposed on the upper side (one side portion) with respect to the piston rod 26 within the head cover 14, and are arranged in a direction orthogonal to the axial direction in a plan view.

[0039] In the head side buffer mechanism 52, the communication cut-off portion 56 is the head side buffer pin 36 and the buffer gasket 44. By the sliding contact of the head side buffer pin 36 and the buffer gasket 44, the communication state between the head side pressure chamber 32 and the head side port 22 is cut off. Further, in the head side buffer mechanism 52, the throttle orifice portion 58 has: an upstream side flow path 62 that communicates with the head side pressure chamber 32 and extends in the axial direction within the head cover 14; a downstream side flow path 64 that is connected to the downstream side of the flow path 62 and extends in the vertical direction within the head cover 14; and a throttle orifice 66 having a diameter smaller than that of the flow path, which connects the lower side of the flow path 64 to the head cover chamber 40. The upper end of the flow path 64 extending in the vertical direction is sealed by a steel ball 68. Therefore, in the case of cutting off the communication state between the head side pressure chamber 32 and the head side port 22, the gas in the head side pressure chamber 32 is discharged from the respective flow paths 62, 64, and the throttle orifice 66 via the head cover chamber 40 and the head side port 22.

[0040] The rod side buffer mechanism 54 has: a communication cut-off portion 70 that cuts off the communication state between the rod side pressure chamber 34 and the rod side port 24 when the piston 30 approaches the end of the stroke; a throttle orifice portion 72 that is provided in the rod cover 16 and discharges the gas in the rod side pressure chamber 34; and a discharge flow rate adjustment portion 74 that is provided in the rod cover 16 and, when the pressure in the rod side pressure chamber 34 exceeds a specified pressure, acts together with the throttle orifice portion 72 to discharge the gas from the rod side pressure chamber 34 (see Figure 1 、 Figure 3A and Figure 3B ). As Figures 1 to 3B shown, the throttle orifice portion 72 and the discharge flow rate adjustment portion 74 are disposed on the upper side (one side portion) with respect to the piston rod 26 within the rod cover 16, and are arranged in a direction orthogonal to the axial direction in a plan view.

[0041] In the rod-side buffer mechanism 54, the communication cut-off portion 70 includes the rod-side buffer pin 38 and the buffer gasket 50. By the sliding contact between the rod-side buffer pin 38 and the buffer gasket 50, the communication state between the rod-side pressure chamber 34 and the rod-side port 24 is cut off. In addition, in the rod-side buffer mechanism 54, the throttle orifice portion 72 has: an upstream flow path 76 that communicates with the rod-side pressure chamber 34 and extends axially within the rod cover 16; a downstream flow path 78 that is connected to the downstream side of the flow path 76 and extends vertically within the rod cover 16; and a throttle orifice 80 having a diameter smaller than that of the flow path 78, which connects the lower side of the flow path 78 to the rod cover chamber 46. The upper end of the flow path 78 extending in the vertical direction is sealed by a steel ball 81. Therefore, when the communication state between the rod-side pressure chamber 34 and the rod-side port 24 is cut off, the gas in the rod-side pressure chamber 34 is discharged to the outside through the flow paths 76, 78, and throttle orifice 80 via the rod cover chamber 46 and the rod-side port 24.

[0042] In the head-side buffer mechanism 52 and the rod-side buffer mechanism 54, the structures of the discharge flow rate adjustment portions 60 and 74 are substantially the same. Therefore, in the following description, mainly with reference to Figures 3A to 4B The discharge flow rate adjustment portion 74 of the rod-side buffer mechanism 54 will be described.

[0043] The discharge flow rate adjustment portion 74 is formed within the rod cover 16 and has: a discharge flow path 82 for discharging the gas in the rod-side pressure chamber 34 to the outside; a spool-type valve element 84 disposed in the middle of the discharge flow path 82; and a spring member 86 (elastic body) that biases the valve element 84 toward the upstream side of the discharge flow path 82.

[0044] The discharge flow path 82 has: a first flow path 82a that communicates with the rod-side pressure chamber 34 and extends axially within the rod cover 16; a second flow path 82b that extends upward from the downstream side of the first flow path 82a; a third flow path 82c having a diameter larger than that of the second flow path 82b and extending upward from the downstream side of the second flow path 82b; and a fourth flow path 82d that is connected to the third flow path 82c and extends axially. Therefore, the connecting portion between the second flow path 82b and the third flow path 82c is formed in a stepped shape.

[0045] In addition, within the rod cover 16, a passage 83 extending from the rod-side pressure chamber 34 toward the third flow path 82c is formed substantially coaxially with the fourth flow path 82d. The passage 83 is a waste hole for forming the fourth flow path 82d using a drill or the like and is sealed by a steel ball 85.

[0046] A tapered portion 88 is formed at a portion of the connecting portion between the second flow path 82b and the third flow path 82c in the inner peripheral surface of the rod cover 16, and the tapered portion 88 has a reduced diameter from the third flow path 82c toward the second flow path 82b.

[0047] The third flow path 82c is sealed by a covering portion 90. The covering portion 90 is fixed to the rod cover 16 by an anti - detachment clip 92. Further, an external thread portion 94 may be formed on the outer peripheral surface of the covering portion 90. In this case, an internal thread portion 96 that engages with the external thread portion 94 is formed at a portion of the third flow path 82c in the inner peripheral surface of the rod cover 16.

[0048] The valve spool 84 is disposed in the range from the second flow path 82b to the third flow path 82c and is a cylindrical spool valve having a step. The valve spool 84 has: a small - diameter portion 84a that can be inserted into the second flow path 82b; and a large - diameter portion 84b having a diameter larger than that of the small - diameter portion 84a, the large - diameter portion 84b being connected to the small - diameter portion 84a and disposed in the third flow path 82c. A sealing member 84c such as an O - ring is provided on the outer peripheral surface of the small - diameter portion 84a, and the sealing member 84c is in sliding contact with a portion of the inner peripheral surface of the rod cover 16 where the second flow path 82b is formed. In addition, the large - diameter portion 84b is in sliding contact with a portion of the inner peripheral surface of the rod cover 16 where the third flow path 82c is formed. On the outer peripheral surface of the large - diameter portion 84b, a slit 84d is formed along the vertical direction, which is the displacement direction of the valve spool 84. In Figure 3B 、 Figure 4A and Figure 4B as an example, a case where two slits 84d are provided is illustrated. Further, the tip portion of the small - diameter portion 84a may be flat like Figure 3B and Figure 4A or may be formed in a needle shape.

[0049] The spring member 86 is inserted between the covering portion 90 and the valve spool 84 in the third flow path 82c. The spring member 86 biases the large - diameter portion 84b in the downward direction (toward the second flow path 82b side).

[0050] The fourth flow path 82d extends axially from the large - diameter portion 84b side of the third flow path 82c and communicates with a flow path 98 (see Figure 2 and Figure 3B ) that extends upward from the rod cover chamber 46. The upper end of the flow path 98 is sealed by a steel ball 100. The fourth flow path 82d communicates with the rod - side port 24 via the flow path 98 and the rod cover chamber 46.

[0051] The discharge flow rate adjustment portion 74 of the rod - side buffer mechanism 54 has been described above. Regarding the discharge flow rate adjustment portion 60 of the head - side buffer mechanism 52, the description of the discharge flow rate adjustment portion 60 can be obtained by changing the statement of "rod" to "head".

[0052] <1.2 Operation of the First Embodiment>

[0053] The operation of the cylinder 10A of the first embodiment configured as described above will be described. Here, the operation of the rod-side buffer mechanism 54 (buffer mechanism) when the piston 30 reaches the stroke end (stroke end) on the rod cover 16 (first cover) side will be described.

[0054] First, at Figure 7 time t1, gas supply starts from the head-side port 22 (second port) to the head-side pressure chamber 32 (second pressure chamber) via the head cover chamber 40, and gas discharge starts from the rod-side pressure chamber 34 (first pressure chamber) via the rod cover chamber 46 and the rod-side port 24 (first port). In addition, in Figure 7 , Ph is the pressure of the gas supplied from the head-side port 22 to the head-side pressure chamber 32 (head-side pressure). Pr is the pressure of the gas discharged from the rod-side port 24 (rod-side pressure). Pc is the pressure of the rod-side pressure chamber 34 (buffer pressure).

[0055] In this case, as time passes from time t1, Ph increases, while Pr decreases. On the other hand, Pc temporarily decreases but generally maintains a specified pressure. As a result, the piston 30 is displaced axially toward the rod cover 16 side, and the piston rod 26 projects axially from the rod cover 16.

[0056] Next, when the rod-side buffer pin 38 enters the rod cover chamber 46 and the rod-side buffer pin 38 comes into sliding contact with the buffer gasket 50 of the rod cover chamber 46, the communication state between the rod-side port 24 and the rod-side pressure chamber 34 via the rod cover chamber 46 is cut off. As a result, the pressure in the rod-side pressure chamber 34 increases. In this case, the gas in the rod-side pressure chamber 34 is discharged from the rod-side port 24 via the throttle hole portion 72 (two flow paths 76, 78, and throttle hole 80) and the rod cover chamber 46 as Figure 5A . If the pressure in the rod-side pressure chamber 34 is equal to or lower than the specified pressure (0.5 MPa in Figure 7 ), the valve element 84 is displaced toward the second flow path 82b side by the force of the spring member 86, and the large-diameter portion 84b blocks the connection portion between the second flow path 82b and the third flow path 82c, cutting off the communication state between the second flow path 82b and the third flow path 82c.

[0057] Next, at time t2, when the pressure in the rod-side pressure chamber 34 exceeds the specified pressure, the valve element 84 is displaced upward (toward the third flow path 82c side) against the force of the spring member 86 due to this pressure. In this case, since a slit 84d is formed in the large-diameter portion 84b, when the valve element 84 is displaced upward, the gas in the space between the cover portion 90 and the valve element 84 is discharged to the fourth flow path 82d side via the slit 84d. As a result, the valve element 84 can be easily displaced upward.

[0058] In addition, the valve spool 84 is a spool-type valve spool that displaces in the upward direction according to the magnitude of the pressure in the rod-side pressure chamber 34. In this case, as Figure 5B shown, the large-diameter portion 84b separates from the connecting portion of the second flow path 82b and the third flow path 82c, and a minute gap is formed between the valve spool 84 (small-diameter portion 84a) and the tapered portion 88. Thereby, the second flow path 82b and the third flow path 82c communicate with each other, and the gas in the rod-side pressure chamber 34 is discharged to the outside from the rod-side port 24 like Figure 5A that through the throttle hole portion 72 and the rod cover chamber 46, and is discharged from the rod-side port 24 like Figure 5B that through the first flow path 82a, the second flow path 82b, the minute gap, the third flow path 82c, the fourth flow path 82d, the flow path 98, and the rod cover chamber 46. That is, when the pressure in the rod-side pressure chamber 34 exceeds the specified pressure, the gas in the rod-side pressure chamber 34 is discharged through two paths. In addition, as the valve spool 84 displaces in the upward direction, the spring member 86 contracts.

[0059] Moreover, when the pressure in the rod-side pressure chamber 34 further rises, the valve spool 84 further displaces in the upward direction, and the gap between the valve spool 84 and the tapered portion 88 becomes larger. That is, the opening degree of the valve spool 84 becomes larger. As a result, the gas in the rod-side pressure chamber 34 is discharged to the outside from the rod-side port 24 like Figure 5A that through the throttle hole portion 72 and the rod cover chamber 46, and is discharged from the rod-side port 24 like Figure 6 that through the first flow path 82a, the second flow path 82b, the larger gap, the third flow path 82c, the fourth flow path 82d, the flow path 98, and the rod cover chamber 46. Also in this case, the gas in the rod-side pressure chamber 34 is discharged through the above two paths. In addition, as the valve spool 84 further displaces in the upward direction, the spring member 86 further contracts.

[0060] Thus, in the time period from time t2 to time t3, the opening degree of the valve spool 84 changes according to the magnitude of the pressure in the rod-side pressure chamber 34, whereby the pressure can be suppressed below the specified pressure and the piston 30 can be brought close to the stroke end side. As a result, at time t3, when the piston 30 reaches the stroke end, the impact force acting on the piston 30 can be reduced.

[0061] <1.3 Effects of the First Embodiment>

[0062] Thus, the cylinder 10A of the first embodiment includes: a cylinder barrel 12 in which a cylinder chamber 28 is formed inside; a first cover (one of the head cover 14 and the rod cover 16) that seals one end of the cylinder barrel 12; a second cover (the other of the head cover 14 and the rod cover 16) that seals the other end of the cylinder barrel 12; a piston 30 that divides the cylinder chamber 28 into a first pressure chamber on the first cover side (one of the head-side pressure chamber 32 and the rod-side pressure chamber 34) and a second pressure chamber on the second cover side (the other of the head-side pressure chamber 32 and the rod-side pressure chamber 34), and the piston 30 slides in the cylinder chamber 28; a piston rod 26 that is connected to the piston 30; a first port (one of the head-side port 22 and the rod-side port 24) that supplies gas to the first pressure chamber and discharges gas from the first pressure chamber; a second port (the other of the head-side port 22 and the rod-side port 24) that supplies gas to the second pressure chamber and discharges gas from the second pressure chamber; and a buffer mechanism (the head-side buffer mechanism 52, the rod-side buffer mechanism 54) that brakes the movement of the piston 30 at least when the piston 30 stops at the stroke end on the first cover side (the start end or the end of the stroke).

[0063] The buffer mechanism has: communication cut-off portions 56, 70 that cut off the communication state between the first pressure chamber and the first port when the piston 30 approaches the stroke end; throttle hole portions 58, 72 that are provided in the first cover and discharge the gas in the first pressure chamber; and discharge flow rate adjustment portions 60, 74 that are provided in the first cover and, when the pressure in the first pressure chamber exceeds a specified pressure, cooperate with the throttle hole portions 58, 72 to discharge the gas from the first pressure chamber.

[0064] The discharge flow rate adjustment portions 60, 74 are formed inside the first cover and have: a discharge flow path 82 for discharging the gas in the first pressure chamber; a spool valve type valve element 84 that is disposed in the middle of the discharge flow path 82; and a spring member 86 (elastic body) that biases the valve element 84 toward the upstream side of the discharge flow path 82.

[0065] Moreover, when the pressure is below the specified pressure, the valve element 84 cuts off the communication state between the upstream side (the second flow path 82b) and the downstream side (the third flow path 82c) of the discharge flow path 82 due to the acting force of the spring member 86. On the other hand, when the pressure exceeds the specified pressure, the valve element 84 is displaced toward the downstream side of the discharge flow path 82 due to the pressure, thereby connecting the upstream side and the downstream side of the discharge flow path 82.

[0066] When the pressure in the first pressure chamber (buffer chamber) is below the specified pressure, the valve element 84 cuts off the communication between the upstream side and the downstream side of the discharge flow path 82 due to the acting force from the spring member 86. Therefore, the gas in the first pressure chamber is discharged only through the throttle hole portions 58 and 72. In addition, when the pressure in the first pressure chamber exceeds the specified pressure, the valve element 84 is displaced due to this pressure, overcoming the acting force, so that the upstream side and the downstream side of the discharge flow path 82 are communicated. Therefore, the gas in the first pressure chamber is discharged through the throttle hole portions 58 and 72 and also through the discharge flow path 82.

[0067] In this way, when the pressure exceeds the specified pressure, the gas in the first pressure chamber is discharged through two paths. As a result, the gas in the first pressure chamber is discharged in a short time, so that the piston 30 can reach the stroke end quickly and smoothly. As a result, the generation of the bounce phenomenon can be avoided, and the responsiveness of the air cylinder 10A can be improved.

[0068] In addition, by displacing the valve element 84 by using the balance between the acting force of the spring member 86 and the pressure in the first pressure chamber, the upstream side and the downstream side of the discharge flow path 82 are switched to the communicated state or the cut-off state. Thereby, manual adjustment of the valve element 84 is not required. That is, since it is a spool-type valve element, when the upstream side and the downstream side of the discharge flow path 82 are in the communicated state, the opening degree of the valve element 84 can be gradually changed according to the magnitude of the pressure in the first pressure chamber.

[0069] Therefore, in the air cylinder 10A, manual adjustment of the valve element 84 is not required, the generation of the bounce phenomenon can be suppressed, and the smooth arrival of the piston 30 at the stroke end and the mitigation of the impact on the piston 30 can be achieved.

[0070] Here, the discharge flow path 82 has: a first flow path 82a that communicates with the first pressure chamber; a second flow path 82b that is connected to the downstream side of the first flow path 82a; a third flow path 82c having a diameter larger than that of the second flow path 82b, which is connected to the downstream side of the second flow path 82b; and a fourth flow path 82d that is connected to the downstream side of the third flow path 82c and communicates with the outside. The valve element 84 has: a small-diameter portion 84a that can be inserted into the second flow path 82b; and a large-diameter portion 84b having a diameter larger than that of the small-diameter portion 84a, which is connected to the small-diameter portion 84a and is disposed in the third flow path 82c. The spring member 86 is disposed in the third flow path 82c and applies a force to the large-diameter portion 84b toward the second flow path 82b side.

[0071] Moreover, when the pressure is below the specified pressure, the valve element 84 is displaced toward the second flow path 82b due to the force of the spring member 86, and the large-diameter portion 84b blocks the connecting portion between the second flow path 82b and the third flow path 82c, thereby cutting off the communication state between the second flow path 82b and the third flow path 82c. In addition, when the pressure exceeds the specified pressure, the valve element 84 overcomes the acting force due to the pressure and is displaced toward the third flow path 82c. As a result, the large-diameter portion 84b separates from the connecting portion, and the second flow path 82b and the third flow path 82c communicate with each other.

[0072] Thereby, the generation of the bounce phenomenon can be effectively suppressed, and the piston 30 can easily reach the stroke end smoothly. In addition, the small-diameter portion 84a bears the pressure of the gas from the first pressure chamber, and the large-diameter portion 84b bears the acting force of the spring member 86. Therefore, the acting force (spring force) to overcome the pressure of the gas can be ensured. That is, since the pressure-receiving area of the gas at the small-diameter portion 84a becomes smaller, the thrust force of the gas acting on the valve element 84 is reduced. Thereby, even if the spring member 86 is miniaturized, the spring force can be ensured.

[0073] In addition, a sealing member 84c is provided on the outer peripheral surface of the small-diameter portion 84a, and the sealing member 84c is in sliding contact with the portion of the second flow path 82b in the inner peripheral surface of the first cover. A tapered portion 88 is formed at the connecting portion in the inner peripheral surface of the first cover, and the tapered portion 88 is reduced in diameter from the third flow path 82c toward the second flow path 82b. Thereby, when the valve element 84 moves in the displacement direction, the generation of wear, damage, etc. of the sealing member 84c caused by contact with the connecting portion is avoided. Therefore, the long life of the cylinder 10A including the valve element 84 can be achieved. In addition, by forming the tapered portion 88, when the valve element 84 is displaced according to the pressure of the gas, the opening degree of the valve element 84 can be gradually changed.

[0074] In addition, a slit 84d is formed on the outer peripheral surface of the large-diameter portion 84b along the displacement direction of the valve element 84. Thereby, when the valve element 84 is displaced toward the third flow path 82c (when the valve element 84 is opened), the gas in the space between the cover portion 90 and the valve element 84 is discharged through the slit 84d. Therefore, the valve element 84 can be easily displaced toward the third flow path 82c.

[0075] In addition, by providing the slit 84d, the pressure-receiving area of the large-diameter portion 84b for the gas in the first pressure chamber becomes smaller. Thereby, when the valve element 84 is displaced toward the second flow path 82b (when the valve element 84 is closed), the force (resistance) received by the large-diameter portion 84b from the gas becomes smaller. Therefore, the valve element 84 can smoothly slide toward the second flow path 82b.

[0076] Moreover, by providing the slit 84d, even if there is play in the large-diameter portion 84b or the inner peripheral surface of the first lid forming the third flow path 82c, the influence of such play on the movement of the valve element 84 can be reduced.

[0077] In addition, the third flow path 82c communicates with the outside and is blocked by the lid portion 90, and a spring member 86 is inserted between the lid portion 90 and the large-diameter portion 84b. Thereby, replacement of the spring member 86 becomes easy.

[0078] In this case, an external thread portion 94 is formed on the outer peripheral surface of the lid portion 90, and an internal thread portion 96 is formed at the portion of the lid portion 90 on the inner peripheral surface of the first lid forming the third flow path 82c, and the internal thread portion 96 is screwed with the external thread portion 94. Thereby, by rotating the lid portion 90, the acting force (spring force) of the spring member 86 can be easily adjusted.

[0079] In addition, the throttle hole portions 58, 72 and the discharge flow rate adjustment portions 60, 74 are centrally arranged on one side portion with respect to the piston rod 26 within the first lid, and thus three of the four surfaces of the first lid can be used as the mounting surfaces of the cylinder 10A. As a result, a plurality of cylinders 10A can be centrally arranged in a limited space. In addition, manufacture of the cylinder 10A becomes easy. Moreover, a cylinder 10A can be realized that maintains interchangeability of the external dimensions with existing products.

[0080] [2. Second Embodiment]

[0081] Next, with reference to Figures 8 to 10 , the cylinder 10B of the second embodiment will be described. In addition, for constituent elements identical to those of the cylinder 10A of the first embodiment (refer to Figures 1 to 7 ), the same reference numerals are given and detailed description thereof is omitted, and the same applies hereinafter.

[0082] The cylinder 10B of the second embodiment differs from the cylinder 10A of the first embodiment in the following aspect: the throttle holes 66, 80 communicate with the second flow path 82b substantially coaxially, and the fourth flow path 82d communicates with the first port (the head-side port 22 or the rod-side port 24). Therefore, in the cylinder 10B of the second embodiment, the throttle holes 66, 80, the second flow path 82b, and the third flow path 82c are formed substantially coaxially, and the first flow path 82a and the second flow path 82b are used as the flow paths of the throttle hole portions 58, 72. Thereby, compared with the cylinder 10A, the number of flow paths within the first lid (the head cover 14 or the rod cover 16) becomes smaller, and machining of this first lid becomes easy.

[0083] The operation of the cylinder 10B of the second embodiment is substantially the same as that of the cylinder 10A of the first embodiment. However, when the piston 30 approaches the stroke end (the start or the end of the stroke), if the pressure in the first pressure chamber (the head-side pressure chamber 32 or the rod-side pressure chamber 34) is below the specified pressure, the gas in the first pressure chamber is discharged through the first flow path 82a, the second flow path 82b, the throttle holes 66 and 80, the first cover chamber (the head cover chamber 40 or the rod cover chamber 46), and the first port. On the other hand, when the pressure in the first pressure chamber exceeds the specified pressure, the valve element 84 is displaced upward, and the second flow path 82b and the third flow path 82c are in a communicating state. Therefore, in addition to the above path, the gas in the first pressure chamber is discharged to the outside through the first flow path 82a to the fourth flow path 82d and the first port.

[0084] Therefore, in the cylinder 10B of the second embodiment, the same effects as those of the cylinder 10A of the first embodiment can also be obtained. In addition, in the case of the second embodiment, compared with the first embodiment, the number of flow paths in the first cover is reduced, so the man-hours for hole machining of the first cover are reduced, and thus the manufacture of the cylinder 10B becomes easier. And, in the second embodiment, since the fourth flow path 82d communicates with the first port, the gas in the first pressure chamber can be discharged quickly to reduce the pressure in the first pressure chamber. As a result, the responsiveness of the cylinder 10B can be improved.

[0085] [3. Third Embodiment]

[0086] Next, with reference to Figure 11A and Figure 11B , the cylinder 10C of the third embodiment will be described.

[0087] The cylinder 10C of the third embodiment is substantially the same in appearance as the cylinder 10B of the second embodiment (refer to Figures 8 to 10 ). However, in the cylinder 10C of the third embodiment, a flow path 102 communicating with the outside is formed in the cover portion 90. This flow path is formed as a fourth flow path 82d that communicates the third flow path 82c with the outside. That is, in the third embodiment, no flow path for discharging gas is formed between the third flow path 82c and the first port (the head-side port 22 or the rod-side port 24). In addition, in Figure 11A and Figure 11B , the case where two fourth flow paths 82d are formed in the cover portion 90 is illustrated.

[0088] The operation of the cylinder 10C of the third embodiment is substantially the same as that of the cylinder 10B of the second embodiment. However, when the pressure in the first pressure chamber exceeds a specified pressure, the valve element 84 is displaced upward, so that the second flow path 82b and the third flow path 82c are in a communicating state. In this case, since a fourth flow path 82d is formed in the cover portion 90, the gas flowing into the third flow path 82c is discharged to the outside (atmosphere) via the slit 84d and the fourth flow path 82d.

[0089] Therefore, in the cylinder 10C of the third embodiment, the same effects as those of the cylinders 10A and 10B of the first and second embodiments can also be obtained. In addition, since the structure is such that the gas flowing into the third flow path 82c is discharged to the outside (atmosphere) via the slit 84d and the fourth flow path 82d, the valve element 84 is displaced toward the third flow path 82c side at a lower pressure, and the gas in the first pressure chamber is discharged smoothly, so that the pressure in the first pressure chamber is rapidly reduced. As a result, the responsiveness of the cylinder 10C is improved. In addition, since there is no need to form a flow path for discharging gas between the third flow path 82c and the first port, the man-hours for hole machining of the first cover are reduced, and thus the manufacture of the cylinder 10C becomes easy.

[0090] In addition, the present invention is not limited to the above-described embodiments, and of course, various structures can be adopted based on the content described in this specification.

Claims

1. A cylinder, comprising: a cylinder barrel, within which a cylinder chamber is formed; a first cover, which seals one end of the cylinder barrel; a second cover, which seals the other end of the cylinder barrel; a piston, which divides the cylinder chamber into a first pressure chamber on the first cover side and a second pressure chamber on the second cover side, and the piston slides within the cylinder chamber; a piston rod, which is connected to the piston; a first port, which supplies gas to the first pressure chamber and discharges gas from the first pressure chamber; a second port, which supplies gas to the second pressure chamber and discharges gas from the second pressure chamber; and a buffer mechanism, which brakes the movement of the piston at least when the piston stops at the stroke end on the first cover side, and the cylinder is characterized in that the buffer mechanism has: a communication cut-off portion, which cuts off the communication state between the first pressure chamber and the first port when the piston approaches the stroke end; a throttle hole portion, which is provided on the first cover and discharges the gas in the first pressure chamber to the outside via the first port; and a discharge flow rate adjustment portion, which is provided on the first cover and, when the pressure in the first pressure chamber exceeds a specified pressure, the discharge flow rate adjustment portion cooperates with the throttle hole portion to discharge gas from the first pressure chamber, the discharge flow rate adjustment portion is formed within the first cover and has: a discharge flow path for discharging the gas in the first pressure chamber; a spool valve type valve element, which is arranged in the middle of the discharge flow path; and an elastic body, which applies a force to the valve element toward the upstream side of the discharge flow path, the discharge flow path has: a first flow path, which communicates with the first pressure chamber; a second flow path, which is connected to the downstream side of the first flow path; a third flow path having a diameter larger than that of the second flow path, which is connected to the downstream side of the second flow path; and a fourth flow path, which is connected to the third flow path and communicates with the outside, the valve element has: a small diameter portion, which can be inserted into the second flow path; and a large diameter portion having a diameter larger than that of the small diameter portion, which is connected to the small diameter portion and is arranged in the third flow path, the elastic body is a spring member arranged in the third flow path and applying a force to the large diameter portion toward the second flow path side, when the pressure is below the specified pressure, the valve element is displaced toward the second flow path side due to the acting force of the spring member, and the large diameter portion blocks the connecting portion between the second flow path and the third flow path, thereby cutting off the communication state between the second flow path and the third flow path, when the pressure exceeds the specified pressure, the valve element overcomes the acting force due to the pressure and is displaced toward the third flow path side, whereby the large diameter portion separates from the connecting portion, so that the second flow path and the third flow path communicate.

2. The cylinder according to claim 1, wherein, A sealing member is provided on the outer peripheral surface of the small-diameter portion, and the sealing member is in sliding contact with the portion of the second flow path in the inner peripheral surface of the first cover. A tapered portion is formed at the portion of the connecting portion in the inner peripheral surface, and the tapered portion tapers from the third flow path toward the second flow path.

3. The cylinder according to claim 1 or 2, wherein, A slit is formed on the outer peripheral surface of the large-diameter portion along the displacement direction of the valve element.

4. The cylinder according to claim 1 or 2, wherein, The third flow path communicates with the outside and is blocked by the cover portion, The spring member is inserted between the cover portion and the large-diameter portion.

5. The cylinder according to claim 4, wherein, An external thread portion is formed on the outer peripheral surface of the cover portion, An internal thread portion is formed at the portion of the cover portion in the inner peripheral surface of the first cover, and the internal thread portion is screwed with the external thread portion.

6. The cylinder according to claim 4, wherein, The first port is formed in the first cover, The second port is formed in the second cover, The throttle hole portion has a throttle hole that discharges the gas flowing from the first pressure chamber through the first flow path and the second flow path to the first port.

7. The cylinder according to claim 6, wherein, The fourth flow path connects the third flow path and the first port.

8. The cylinder according to claim 6, wherein, The fourth flow path is formed in the cover portion and communicates the third flow path with the outside.

9. The cylinder according to claim 1 or 2, wherein, The throttle hole portion and the discharge flow rate adjustment portion are centrally arranged on one side portion with respect to the piston rod in the first cover.

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