Air cylinder

Abstract

Air cylinder (10), comprising: a cylinder tube (12) having a through hole (26) extending in the axial direction; a first cover (18) configured to seal an end portion of the through-hole in a first direction of the through-hole; a second cover (20) configured to seal an end portion of the through-hole in a second direction of the through-hole and to form a cylinder chamber (28) between the first cover and the second cover; a piston (14) configured to divide the cylinder chamber into a first pressure chamber (30) and a second pressure chamber (32); a first opening (70) formed in the cylinder tube and through which compressed air is supplied to and discharged from the first pressure chamber; a first damping chamber (58) formed in the first cover and configured to communicate with the first pressure chamber; a first damping projection (44) configured to protrude from the piston in the first direction and block communication between the first pressure chamber and the first damping chamber when inserted into the first damping chamber; a first internal flow path (62) connecting the first damping chamber and the first opening; and a first throttle flow path (64) formed in the first cover, having an effective area smaller than an effective area of the first inner flow path, and configured to connect the first pressure chamber and the first opening, wherein the first throttle flow path is formed in the first cover and is connected to the first inner flow path within the first cover.

Description

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0001] The present invention relates to an air cylinder (pneumatic cylinder) with an air damping mechanism. DESCRIPTION OF THE STATE OF THE ART

[0002] In some cases, an air cylinder uses an air cushion mechanism to cushion the impact caused by inertia when a piston stops at the stroke end. For example, JP 2000-199503 A discloses an air cushion mechanism that includes a main flow path allowing a large flow rate in a cylinder tube and a throttle flow path in which a throttle valve is provided. In this air cylinder, the main flow path is blocked when the piston is displaced near the stroke end. By limiting the discharge flow rate, the piston is decelerated. SUMMARY OF THE INVENTION

[0003] The conventional air damping mechanism requires a main flow path, a throttle flow path, and a throttle valve for a port. To efficiently implement these structures in a cylinder tube, the throttle flow path extends axially, and the throttle valves are arranged in the axial direction of the ports.

[0004] However, if the axial length of the cylinder tube is to be reduced, the space for arranging the throttle valves and ports may be insufficient. For example, if the piston stroke is short, the two ports must be arranged close to each other in the axial direction to provide space for the throttle valves, and the joints will interfere with each other, resulting in connection problems. Therefore, the conventional air cushion mechanism has the disadvantage that it can only be mounted on an air cylinder with a stroke length greater than or equal to a specified length.

[0005] The present invention aims to solve the problem described above.

[0006] One aspect of the present invention is characterized by an air cylinder provided with a cylinder tube having a through-hole extending in the axial direction, a first cover configured to seal an end portion of the through-hole in a first direction of the through-hole, a second cover configured to seal an end portion of the through-hole in a second direction of the through-hole and forming a cylinder chamber between the first cover and the second cover, a piston configured to divide the cylinder chamber into a first pressure chamber and a second pressure chamber, a first opening formed in the cylinder tube through which compressed air is supplied to and discharged from the first pressure chamber, a first damping chamber formed in the first cover and configured tothat it communicates with the first pressure chamber, a first damping protrusion configured to protrude from the piston in the first direction and block the communication between the first pressure chamber and the first damping chamber when inserted into the first damping chamber, a first internal flow path connecting the first damping chamber and the first opening, and a first throttle flow path formed in the first cover and having an effective area smaller than an effective area of the first internal flow path and configured to connect the first pressure chamber and the first opening, wherein the first throttle flow path is formed in the first cover and connected to the first internal flow path within the first cover.

[0007] According to the present invention, the first throttle flow path for throttling the exhaust gas at the stroke end is integrated into the first cover. Therefore, the air cylinder does not require the provision of a throttle valve in the cylinder tube and can be equipped with an air damping mechanism for throttling the exhaust gas even when the stroke length is shorter.

[0008] The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of an air cylinder according to an embodiment, showing a state in which a piston is positioned at a stroke end in a first direction; Fig. 2A is a partially enlarged cross-sectional view of the vicinity of a first cover shown in Fig. 1 is shown, and Fig. 2B is a partially enlarged cross-sectional view of the vicinity of a second cover shown in Fig. 1 is shown; Fig. 3 is a cross-sectional view of the Fig. 1 shown air cylinder in an intermediate position of its stroke; and Fig. 4 is a cross-sectional view at the stroke end in a second direction of the Fig. 1 shown air cylinder. DETAILED DESCRIPTION OF THE INVENTION

[0009] An air cylinder 10 according to the present embodiment, which is shown in Fig. 1 is a double-acting cylinder that operates by supplying and discharging compressed air. The air cylinder 10 is used, for example, in an automated production line in a factory or the like. In the following description, the direction along a central axis line C of a cylinder tube 12 of the air cylinder 10 is referred to as an axial direction (a first direction and a second direction). A direction perpendicular to the axial direction and away from the axial direction is referred to as a diametrical outward direction or outward direction, and a direction perpendicular to the axial direction and facing the axial direction is referred to as a diametrical inward direction or inward direction. Among the diametrical directions, a direction in which an orifice is formed is referred to as an upward direction, and the opposite direction thereto is referred to as a downward direction.Furthermore, in the following description, the terms “top” and “bottom” are used to describe a relative positional relationship between the components of the air cylinder 10 and are not intended to limit the direction in which the air cylinder 10 is arranged.

[0010] The air cylinder 10 includes the cylinder tube 12, a piston 14, a piston rod 16, a first cover 18 (a head cover), a second cover 20 (a rod cover), a first air damping mechanism 22, and a second air damping mechanism 24. A through hole 26 extending in a straight line is formed inside the cylinder tube 12. The first cover 18 is inserted into the through hole 26 near one end portion in the first direction, and the second cover 20 is inserted into the through hole 26 near one end portion in the second direction. The first cover 18 and the second cover 20 seal both ends of the through hole 26, thus forming a cylinder chamber 28 therein.

[0011] The first cover 18 and the second cover 20 are mounted so that the entire body is axially disposed inside the through hole 26 and does not protrude axially from the cylinder tube 12. Therefore, the axial dimension of a portion excluding the piston rod 16 of the air cylinder 10 corresponds to the length of the cylinder tube 12. Such an air cylinder 10 can be axially small.

[0012] The piston 14 is housed in the cylinder chamber 28. The piston 14 hermetically divides the cylinder chamber 28 into a first pressure chamber 30 in a first direction and a second pressure chamber 32 in a second direction. The piston 14 hermetically divides the cylinder chamber 28 and slides axially inside the cylinder tube 12.

[0013] A piston seal 34, a magnet 36, and a wear ring 38 are attached to an outer peripheral portion of the piston 14. The piston seal 34 hermetically seals the first pressure chamber 30 and the second pressure chamber 32 from each other by preventing compressed air from escaping along a gap between the piston 14 and the cylinder tube 12. The magnet 36 enables the piston position to be detected by a magnetic sensor (not shown). The wear ring 38 prevents rattling of the piston 14 and stabilizes the displacement of the piston 14 in the axial direction.

[0014] An annular first damper 40 is attached to an end surface 14a of the piston 14 in the first direction. The first damper 40 is made of an elastic material and reduces the impact caused by the collision between the piston 14 and the first cover 18. An annular second damper 42 is attached to an end surface 14b of the piston 14 in the second direction. The second damper 42 reduces the impact caused by the collision between the piston 14 and the second cover 20.

[0015] The piston 14 has a first damping protrusion 44 that protrudes in a first direction from the end surface 14a in the first direction. The first damping protrusion 44 is formed on a first rod portion 48 that forms part of the piston rod 16 in the first direction. The first damping protrusion 44 is a cylindrical portion with an outer diameter smaller than that of the piston 14, and its distal end is tapered.

[0016] The first damping protrusion 44 forms a part of the first air damping mechanism 22. More specifically, the first damping protrusion 44 is inserted into a first damping chamber 58 described later at a stroke end in the first direction of the piston 14 and prevents the compressed air from escaping through a first internal flow path 62.

[0017] The piston 14 has a second damping protrusion 46 that protrudes outward from the end surface 14b in the second direction. Furthermore, the second damping protrusion 46 may be integrally formed with the piston 14. The second damping protrusion 46 is formed to have a diameter larger than that of the piston rod 16. A portion of the second damping protrusion 46 covers the outer peripheral surface of the piston rod 16.

[0018] The second damping protrusion 46 forms a part of the second air damping mechanism 24. More specifically, the second damping protrusion 46 is inserted into a second damping chamber 72 described later at a stroke end in the second direction and prevents the compressed air from escaping through a second internal flow path 76.

[0019] The piston rod 16 is connected to the piston 14 and extends in the axial direction. The piston rod 16 is provided with a first rod part 48 for holding the piston 14 from the first direction and a second rod part 50 for holding the piston 14 from the second direction. The first rod part 48 has a first damping projection 44 protruding in the first direction relative to the piston 14, a penetrating portion 52 inserted into a central bore 14c of the piston 14, and a connecting portion 54 connected to the second rod part 50. The connecting portion 54 is inserted into a connecting hole 56 of the second rod part 50 and connected to the second rod part 50.

[0020] The second rod portion 50 is received in a receiving hole 14d of the piston 14 and holds the piston 14 from the second direction. The piston 14 is connected to the piston rod 16 so as to be disposed between the first rod portion 48 and the second rod portion 50 in the axial direction. The second rod portion 50 is inserted through an insertion hole 20a of the second cover 20 and protrudes from the second cover 20 in the first direction. The piston rod 16 is displaced in the axial direction together with the piston 14.

[0021] The first cover 18 includes the first damping chamber 58, a first damping seal 60, the first inner flow path 62, and a first throttle flow path 64.

[0022] The first damping chamber 58 is formed by recessing in the first direction an end portion in the second direction of the first cover 18. The first damping chamber 58 is positioned in the center of the first cover 18 and opens into the first pressure chamber 30. The first damping chamber 58 has an inner diameter and an axial dimension larger than those of the first damping protrusion 44 and can accommodate the first damping protrusion 44.

[0023] A first seal receiving groove 58a is formed near an end portion in the second direction of the first damping chamber 58. The first damping seal 60 is mounted in the first seal receiving groove 58a. When the first damping protrusion 44 is inserted into the first damping chamber 58, the first damping seal 60 comes into airtight contact with the first damping protrusion 44, thereby preventing communication between the first damping chamber 58 and the first pressure chamber 30. More specifically, by abutting against the first damping protrusion 44, the first damping seal 60 prevents the compressed air from escaping through the first internal flow path 62.

[0024] As in Fig. 1 and Fig. 2A, the first inner flow path 62 extends in the up / down direction and penetrates the first cover 18 in the diametrical direction. A central portion of the first inner flow path 62 opens into and communicates with the first damping chamber 58. More specifically, the first inner flow path 62 communicates with the first pressure chamber 30 via the first damping chamber 58. The outer peripheral end portion of the first inner flow path 62 communicates with a first opening 70 formed in the upper portion of the cylinder tube 12. The first inner flow path 62 has a comparatively large effective area and can quickly perform the supply and discharge of compressed air to and from the first pressure chamber 30.

[0025] The first throttle flow path 64 is located radially outside the first damping chamber 58. The first throttle flow path 64 extends in the axial direction, and an end portion thereof in the first direction is connected to the first inner flow path 62 in the first cover 18. The end portion of the first throttle flow path 64 in the second direction is open to the first pressure chamber 30. The first throttle flow path 64 has an effective area smaller than that of the first inner flow path 62. Accordingly, the first throttle flow path 64 delays the discharge of the compressed air from the first pressure chamber 30. The first throttle flow path 64 is arranged to overlap the first damping chamber 58 in the radial direction.Since the position of the first throttle flow path 64 overlaps the first damping chamber 58 and the first opening 70 in the axial direction, the first throttle flow path 64 can be provided without increasing the length of the air cylinder 10 in the axial direction.

[0026] A first outer peripheral seal 66a, a second outer peripheral seal 66b, and a first retaining ring 68 are attached to an outer peripheral portion of the first cover 18. The first outer peripheral seal 66a is positioned on one side in the first direction of the first inner flow path 62, and the second outer peripheral seal 66b is positioned on one side in the second direction of the first inner flow path 62. The first outer peripheral seal 66a and the second outer peripheral seal 66b prevent the compressed air from escaping through a gap between the first cover 18 and the cylinder tube 12.

[0027] The first retaining ring 68 fixes the first cover 18 to the cylinder tube 12. The first retaining ring 68 fits into a groove-shaped concave part formed in the first cover 18 and the cylinder tube 12 and serves to prevent the first cover 18 from being displaced in the axial direction relative to the cylinder tube 12.

[0028] As in Fig. 1, the second cover 20 includes the insertion port 20a, the second damping chamber 72, a second damping seal 74, the second internal flow path 76, and a second throttle flow path 78. The insertion port 20a penetrates a central portion of the second cover 20 in the axial direction. The piston rod 16 is inserted through the insertion port 20a. A rod seal 80 is installed in a predetermined portion of the insertion port 20a. The rod seal 80 prevents the compressed air from escaping through a gap between the piston rod 16 and the second cover 20.

[0029] The second damping chamber 72 is concavely formed by a recess in the second direction at one end portion in the first direction of the second cover 20. The second damping chamber 72 opens to the first direction side of the second damping chamber 72 and communicates with the second pressure chamber 32. The second damping chamber 72 is positioned in the center of the second cover 20 and has an inner diameter and axial length larger than those of the second damping projection 46. The second damping chamber 72 serves to accommodate the second damping projection 46 when the piston 14 is displaced in the second direction near the stroke end.

[0030] As in Fig. 2B and Fig. 4, a second seal receiving groove 72a is formed near an end portion in the first direction of the second damping chamber 72. The second seal 74 is mounted in the second seal receiving groove 72a. When the second damping protrusion 46 is inserted into the second damping chamber 72, the second seal 74 comes into airtight contact with the second damping protrusion 46, thereby preventing communication between the second damping chamber 72 and the second pressure chamber 32. More specifically, the second damping seal 74 comes into airtight contact with the second damping protrusion 46 near the stroke end in the second direction, blocking the escape of the compressed air from the second pressure chamber 32 through the second internal flow path 76.

[0031] The second inner flow path 76 extends in the up / down direction and penetrates the second cover 20 in the diametrical direction. A central portion of the second inner flow path 76 opens into and communicates with the second damping chamber 72. The outer peripheral end portion of the second inner flow path 76 communicates with a second opening 82 formed in the upper portion of the cylinder tube 12. The second inner flow path 76 has a comparatively large effective area and can quickly supply and discharge compressed air to and from the second pressure chamber 32.

[0032] As in Fig. 2B, the second throttle flow path 78 is located radially outside the second damping chamber 72. The second throttle flow path 78 extends in the axial direction. The end portion of the second throttle flow path 78 in the first direction is open to the second pressure chamber 32. The end portion of the second throttle flow path 78 in the second direction is connected to the second inner flow path 76 in the second cover 20. The second throttle flow path 78 has a smaller effective area than the second inner flow path 76. Since the position of the second throttle flow path 78 overlaps the second damping chamber 72 and the second opening 82 in the axial direction, the second throttle flow path 78 can be provided without increasing the length of the air cylinder 10 in the axial direction.

[0033] A third outer peripheral seal 84a and a fourth outer peripheral seal 84b are attached to an outer peripheral portion of the second cover 20. The third outer peripheral seal 84a is positioned on one side in the first direction of the second inner flow path 76, and the fourth outer peripheral seal 84b is positioned on one side in the second direction of the second inner flow path 76. The third outer peripheral seal 84a and the fourth outer peripheral seal 84b prevent the compressed air from escaping through a gap between the second cover 20 and the cylinder tube 12.

[0034] A second retaining ring 86 is attached to one end portion in the second direction of the second cover 20. The second retaining ring 86 fixes the second cover 20 to the cylinder tube 12. The second retaining ring 86 is a metallic member formed in a C-shape and fits into a groove-shaped concave portion formed in the cylinder tube 12, and serves to prevent the second cover 20 from being displaced in the axial direction relative to the cylinder tube 12.

[0035] As in Fig. 1 and Fig. 2A, the first air damping mechanism 22 includes the first damping protrusion 44, the first damping chamber 58, the first damping seal 60, the first internal flow path 62, and the first throttle flow path 64. The first air damping mechanism 22, by the first damping protrusion 44 and the first damping seal 60 coming into contact with each other near the stroke end in the first direction, isolates the first damping chamber 58 from the first pressure chamber 30. The first air damping mechanism 22 closes the first internal flow path 62 and the first pressure chamber 30, thereby restricting the compressed air from the first pressure chamber 30 through the first throttle flow path 64 and reducing the speed of the piston 14.

[0036] As in Fig. 1, the first opening 70 and the second opening 82 are formed in the cylinder tube 12. The first opening 70 is located near the end of the cylinder tube 12 in the first direction. The first opening 70 is arranged so that the first damping chamber 58 and the first throttle flow path 64 are superimposed on each other in the axial direction, thereby enabling the air cylinder 10 to be shortened in the axial direction. A compressed air line (not shown) is connected to the first opening 70, whereby compressed air is supplied to and discharged from the first pressure chamber 30. The second opening 82 is located near the end of the cylinder tube 12 in the second direction. The second opening 82 is arranged so that their axial positions overlap those of the second damping chamber 72 and the second throttle flow path 78, thereby enabling the axial shortening of the air cylinder 10.A compressed air line (not shown) is connected to the second opening 82, whereby compressed air is supplied into and discharged from the second pressure chamber 32.

[0037] The air cylinder 10 is constructed as described above. The operation of the air cylinder 10 is described below.

[0038] In the Fig. In the air cylinder 10 shown in Figure 1, the piston 14 is positioned at the stroke end in the first direction. When a compressed air supply source is connected to the first port 70 and an exhaust port is connected to the second port 82, the compressed air flows through the first throttle flow path 64 and is supplied to the first pressure chamber 30. According to this feature, a pressure difference is created between the first pressure chamber 30 and the second pressure chamber 32, and the piston 14 starts to displace in the second direction. When the first cushioning protrusion 44 is separated from the first cushioning seal 60, the first cushioning chamber 58 and the first pressure chamber 30 are connected to each other, and a larger flow rate of the compressed air is supplied to the first pressure chamber 30 via the first internal flow path 62. According to this feature, the speed of the piston 14 in the second direction is increased.

[0039] As in Fig. 3, at an intermediate position of the stroke, the first internal flow path 62 and the first throttle flow path 64 communicate with the first pressure chamber 30, and the second internal flow path 76 and the second throttle flow path 78 communicate with the second pressure chamber 32. Since the discharge of the compressed air in the second pressure chamber 32 occurs quickly via the second internal flow path 76 and the second throttle flow path 78, the piston 14 moves quickly.

[0040] As in Fig. 4, when the piston 14 is displaced in the second direction to the stroke end, the second cushioning protrusion 46 is inserted into the second cushioning chamber 72. This brings the second cushioning seal 74 and the second cushioning protrusion 46 into airtight contact with each other, and isolates the second cushioning chamber 72 from the second pressure chamber 32. According to this feature, the second internal flow path 76 is isolated from the second pressure chamber 32. Thereafter, the compressed air in the second pressure chamber 32 is discharged via the second throttle flow path 78. The second throttle flow path 78 acts to reduce the speed of the piston 14 to a range where an impact can be absorbed by the second damper 42 by limiting the outflow amount of the compressed air. As described above, the second air cushioning mechanism 24 cushions the impact at the end of the stroke in the second direction.

[0041] Thereafter, when the exhaust port is connected to the first port 70 and the compressed air supply source is connected to the second port 82, the compressed air flows through the second internal flow path 76 and the second throttle flow path 78 and is supplied to the second pressure chamber 32. According to this feature, the piston 14 performs a stroke in the first direction.

[0042] During its stroke in the first direction, the piston 14 is driven by the Fig. 3 shown intermediate position of the stroke into the Fig.1 in the first direction. Near the stroke end in the first direction, the first cushioning protrusion 44 is inserted into the first cushioning chamber 58. As a result, the first seal 60 and the first cushioning protrusion 44 abut each other airtight, and the first cushioning chamber 58 and the first pressure chamber 30 are isolated from each other. The first internal flow path 62 is isolated from the first pressure chamber 30. Thereafter, the compressed air in the first pressure chamber 30 is discharged via the first throttle flow path 64. The first throttle flow path 64 acts to reduce the speed of the piston 14 to a range where an impact can be absorbed by the first damper 40 by limiting the flow amount of the discharged compressed air. As described above, the first air cushioning mechanism 22 dampens the impact at the end of the stroke in the first direction.

[0043] Since the first air damping mechanism 22 is formed within the first cover 18 and the second air damping mechanism 24 is formed within the second cover 20 in the air cylinder 10, it is not necessary to provide a throttle valve or a throttle flow path in the cylinder tube 12. Therefore, the overall length of the cylinder tube 12 can be shortened and the dimension of the air cylinder 10 in the axial direction can be reduced.

[0044] The following supplementary notes are further disclosed with respect to the embodiments described above. Supplementary Note 1

[0045] The air cylinder (10) according to the present disclosure includes the cylinder tube (12) having the through-hole (26) extending in the axial direction, the first cover (18) configured to seal the end portion of the through-hole in the first direction of the through-hole, the second cover (20) configured to seal the end portion of the through-hole in the second direction of the through-hole and form the cylinder chamber (28) between the first cover and the second cover, the piston (14) configured to divide the cylinder chamber into the first pressure chamber (30) and the second pressure chamber (32), the first orifice (70) formed in the cylinder tube and through which compressed air is supplied to and discharged from the first pressure chamber, the first damping chamber (58) formed in the first cover and configured tothat it communicates with the first pressure chamber, wherein the first damping projection (44) is configured to protrude from the piston in the first direction and to block the communication between the first pressure chamber and the first damping chamber when inserted into the first damping chamber, wherein the first internal flow path (62) connects the first damping chamber and the first opening, and wherein the first throttle flow path (64) is formed in the first cover, the effective area of which is smaller than the effective area of the first internal flow path and is configured to connect the first pressure chamber and the first opening, wherein the first throttle flow path is formed in the first cover and is connected to the first internal flow path within the first cover.

[0046] The air cylinder described above does not require a throttle valve or the like in the cylinder tube, which can reduce the overall length of the air cylinder. Supplementary Note 2

[0047] In the air cylinder according to Supplementary Note 1, the first internal flow path may extend in a radial direction intersecting the axial direction in the first cover, and the first throttle flow path may extend in the axial direction in the first cover and be connected to the first internal flow path. In such an air cylinder, it is possible to form an air damping mechanism in the first cover in a simple and compact manner. Supplementary Note 3

[0048] In the air cylinder according to Supplementary Note 1 or 2, the first throttle flow path may be arranged outside the first damping chamber and parallel thereto. Such an air cylinder may limit the dimension of the first cover in the axial direction. Supplementary Note 4

[0049] In the air cylinder according to Supplementary Note 1, the first throttle flow path, the first damping chamber, and the first orifice may be arranged to overlap in the radial direction intersecting the axial direction. In such an air cylinder, the first throttle flow path, the first damping chamber, and the first orifice can be efficiently arranged in the axial direction, and the dimension in the axial direction can be limited. Supplementary Note 5

[0050] In the air cylinder according to any one of Supplementary Notes 1 to 4, there may be further provided: the second opening (82) formed in the cylinder tube and through which compressed air is supplied to and discharged from the second pressure chamber, the second damping chamber (72) formed in the second cover and configured to communicate with the second pressure chamber, the second internal flow path (76) connecting the second damping chamber and the second opening, the second damping projection (46) formed to protrude from the piston in the second direction and block the communication between the second internal flow path and the second pressure chamber when inserted into the second damping chamber, and the second throttle flow path (78) formed in the second cover and having an effective area smaller than the effective area of the second internal flow path,and which is configured to connect the second pressure chamber and the second opening, wherein the second throttle flow path may be connected to the second internal flow path within the second cover. Such an air cylinder may be provided with the air damping mechanism at the end portion on the second opening side while keeping the dimension in the axial direction small. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2000-199503 A

[0002]

Claims

[1] Air cylinder (10), comprising: a cylinder tube (12) having a through hole (26) extending in the axial direction; a first cover (18) configured to seal an end portion of the through-hole in a first direction of the through-hole; a second cover (20) configured to seal an end portion of the through-hole in a second direction of the through-hole and to form a cylinder chamber (28) between the first cover and the second cover; a piston (14) configured to divide the cylinder chamber into a first pressure chamber (30) and a second pressure chamber (32); a first opening (70) formed in the cylinder tube and through which compressed air is supplied to and discharged from the first pressure chamber; a first damping chamber (58) formed in the first cover and configured to communicate with the first pressure chamber; a first damping projection (44) configured to protrude from the piston in the first direction and to block communication between the first pressure chamber and the first damping chamber when inserted into the first damping chamber; a first internal flow path (62) connecting the first damping chamber and the first opening; and a first throttle flow path (64) formed in the first cover, having an effective area smaller than an effective area of the first inner flow path, and configured to connect the first pressure chamber and the first opening, wherein the first throttle flow path is formed in the first cover and is connected to the first inner flow path within the first cover. [2] The air cylinder according to claim 1, wherein the first inner flow path extends in a radial direction intersecting the axial direction in the first cover, and the first throttle flow path extends in the axial direction in the first cover and is connected to the first inner flow path. [3] The air cylinder according to claim 1, wherein the first throttle flow path is arranged outside the first damping chamber and parallel to the first damping chamber. [4] The air cylinder according to claim 1, wherein the first throttle flow path, the first damping chamber and the first orifice are arranged to overlap in a radial direction intersecting the axial direction. [5] An air cylinder according to any one of claims 1 to 4, further comprising: a second opening (82) formed in the cylinder tube and through which compressed air is supplied to and discharged from the second pressure chamber; a second damping chamber (72) formed in the second cover and configured to communicate with the second pressure chamber; a second internal flow path (76) connecting the second damping chamber and the second opening; a second damping projection (46) configured to protrude from the piston in the second direction and to block communication between the second internal flow path and the second pressure chamber when inserted into the second damping chamber; and a second throttle flow path (78) formed in the second cover, having an effective area smaller than an effective area of the second inner flow path, and configured to connect the second pressure chamber and the second opening, wherein the second throttle flow path is connected to the second inner flow path within the second cover.

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