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 in a first direction of the through hole; a second cover (20) configured to seal an end portion 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 can be supplied into 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 damping chamber and the first pressure chamber when inserted into the first damping chamber; a first main flow path (63) configured to communicate with the first damping chamber; and a first fixed opening (64) having an effective area smaller than an effective area of the first main flow path and configured to open into the first pressure chamber; wherein the first main flow path and the first fixed opening open at a bottom surface (70a) of the first opening.

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] In a conventional air cylinder, a cushion seal is used to block the main flow path. Since air leakage from the cushion seal will lead to a reduction in cushioning performance, it is desirable to inspect the cushion seal at the time of shipment or, alternatively, periodically during use. However, it is difficult to directly verify the sealing performance of a conventional cushion seal, so the sealing performance of the cushion seal is verified by checking the deceleration at the end of the piston stroke.

[0004] Therefore, there is a long-awaited need for an air cylinder capable of more directly checking seal air leakage through a simpler method.

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

[0006] One aspect of the present invention is characterized by an air cylinder comprising: a cylinder tube having a through-hole extending in the axial direction, a first cover configured to seal an end portion in a first direction of the through-hole, a second cover configured to seal an end portion 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 can be supplied to and discharged from the first pressure chamber, a first damping chamber formed in the first cover and configured to communicate with the first pressure chamber,a first damping protrusion configured to protrude from the piston in the first direction and block communication between the first damping chamber and the first pressure chamber when inserted into the first damping chamber, a first main flow path configured to communicate with the first damping chamber, and a first fixed opening having an effective area configured to be smaller than an effective area of the first main flow path and configured to open into the first pressure chamber, the first main flow path and the first fixed opening opening at a bottom surface of the first opening.

[0007] According to the present invention, by checking whether the piston has stopped before the stroke end in a state where the first fixed hole exposed at the bottom surface of the first hole is blocked with a rubber rod or the like, the sealing performance of the cushion packing can be easily and reliably checked.

[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 a first 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 air cylinder used in Fig. 1 is shown in an intermediate position of its stroke; Fig. 4 is a cross-sectional view at the stroke end in a second direction of the Fig. 1 shown air cylinder; and Fig. 5A is a partially enlarged cross-sectional view of the vicinity of the first cover of the air cylinder according to a first aspect of a second embodiment, and Fig. 5B is a partially enlarged cross-sectional view of the vicinity of the first cover of the air cylinder according to a second aspect of the second embodiment. DETAILED DESCRIPTION OF THE INVENTIONFirst Embodiment

[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 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). Further, 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 closer to 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 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 close both ends of the through-hole 26, thus forming a cylinder chamber 28 therein.

[0011] A first opening 70 is formed near an end portion of the cylinder tube 12 in the first direction, and a second opening 82 is formed near an end portion of the cylinder tube 12 in the second direction. Air pipes are connected to the first opening 70 and the second opening 82, respectively, and serve to supply compressed air for driving the air cylinder 10 and to exhaust the compressed air.

[0012] A first main flow path 63 and a first fixed opening 64 open into a bottom surface 70a of the first opening 70. The first main flow path 63 is positioned near an end portion in the first direction of the bottom surface 70a, and the first fixed opening 64 is positioned near an end portion in the second direction of the bottom surface 70a. The first fixed opening 64 is positioned on a side farther in the second direction than the end portion in the second direction of the first cover 18, and its position in the axial direction overlaps with a first pressure chamber 30 described later. The first fixed opening 64 extends in a straight line in the diametrical direction, and an end portion on an inner peripheral side thereof opens into the first pressure chamber 30.

[0013] The first main flow path 63 has an effective area larger than that of the first fixed orifice 64, and compressed air with a larger flow rate than the first fixed orifice 64 can flow through it. An axial position of the first main flow path 63 overlaps an axial position of a first inner flow path 62 described later. The first main flow path 63 is formed as a hole extending briefly in the diametrical direction and communicating with the first inner flow path 62. As mentioned above, the first main flow path 63 and the first fixed orifice 64 can be formed as holes extending in the diametrical direction, and each of them can be formed by only one drilling process, thereby making their manufacture easy.

[0014] A second main flow path 77 and a second fixed opening 78 open into a bottom surface 82a of the second opening 82. The second main flow path 77 is positioned near an end portion in the second direction of the bottom surface 82a, and the second fixed opening 78 is positioned near an end portion in the first direction of the bottom surface 82a. The second fixed opening 78 is positioned on a side farther in the first direction than an end portion in the first direction of the second cover 20, and its position in the axial direction overlaps with a second pressure chamber 32 described later. The second fixed opening 78 is formed as a hole extending in the diametrical direction (downward), and an end portion on an inner peripheral side thereof opens into the second pressure chamber 32.

[0015] The second main flow path 77 has an effective area larger than that of the second fixed orifice 78, and a larger flow rate of compressed air flows through it than through the second fixed orifice 78. The second main flow path 77 is formed as a hole extending in the diametrical direction, and its axial position coincides with the axial position of a second internal flow path 76 described later. The second fixed orifice 78 acts to decelerate the piston 14 by limiting the flow rate of compressed air discharged in the second direction near the stroke end. The second main flow path 77 and the second fixed orifice 78 are formed as holes extending in the diametrical direction and are therefore easy to manufacture.

[0016] 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.

[0017] The piston 14 is housed in the cylinder chamber 28. The piston 14 divides the cylinder chamber 28 in a first direction into the first pressure chamber 30 and in a second direction into the second pressure chamber 32. The piston 14 divides the cylinder chamber 28 in an airtight manner and slides axially inside the cylinder tube 12.

[0018] 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.

[0019] The piston 14 includes a first damping protrusion 44 projecting outwardly from an end surface 14a in a first direction. The first damping protrusion 44 is a cylindrical portion having an outer diameter smaller than that of the piston 14 and a distal end tapered into a conical shape. Although not specifically limited to this feature, the first damping protrusion 44 is integrally formed with the piston 14.

[0020] 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 the first internal flow path 62.

[0021] A second cushioning protrusion 46, which protrudes in a second direction, is attached to an end surface 14b in the second direction of the piston 14. The second cushioning protrusion 46 is a cylindrical member covering an outer peripheral part of the piston rod 16 and having an outer diameter larger than the outer diameter of the piston rod 16. The second cushioning protrusion 46 is received in a receiving hole 14d of the piston 14. When inserted into a second cushioning chamber 72 described later, the second cushioning protrusion 46 airtightly abuts against a second cushioning packing 74 and prevents the compressed air from escaping via the second main flow path 77. Furthermore, the second cushioning protrusion 46 may be formed integrally with the piston 14.

[0022] A mounting hole 14c and a receiving hole 14d are formed in a central part of the piston 14. The mounting hole 14c is positioned in a diametrically inward direction of the magnet 36, and a small-diameter portion 16a of the piston rod 16 is inserted therein. The receiving hole 14d is formed adjacent to a second-direction side of the mounting hole 14c. The receiving hole 14d has an inner diameter larger than that of the mounting hole 14c and receives a part of a first-direction side of a large-diameter portion 16b of the piston rod 16 and a part of a first-direction side of the second cushion protrusion 46.

[0023] The piston rod 16 is connected to the piston 14 and extends in the axial direction. The piston rod 16 includes the small-diameter portion 16a and the large-diameter portion 16b. The small-diameter portion 16a is inserted into the mounting hole 14c of the piston 14 and connected to the piston 14 by crimping or a similar method. The large-diameter portion 16b of the piston rod 16 extends from the piston 14 in the second direction in the axial direction. The large-diameter portion 16b of the piston rod 16 passes through the second cover 20 and protrudes from the second cover 20 in the first direction. The piston rod 16 is displaced together with the piston 14 in the axial direction.

[0024] An end portion of the first cover 18 in the second direction is positioned on a side farther in the first direction than the first fixed opening 64, thereby enabling communication between the first fixed opening 64 and the first pressure chamber 30. The first cover 18 includes the first damping chamber 58, a first damping seal 60, and the first internal flow path 62.

[0025] The first damping chamber 58 is formed by a recess in the first direction in 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 that are larger than those of the first damping protrusion 44 and can accommodate the first damping protrusion 44.

[0026] 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.

[0027] 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 middle 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. An upper end of the first inner flow path 62 is connected to the first main flow path 63 formed in an upper part of the cylinder tube 12. The first main flow path 63 is a flow path that opens at the bottom surface 70a of the first opening 70 of the cylinder tube 12 and serves to connect the first opening 70 and the first inner flow path 62.The first inner flow path 62 and the first main flow path 63 have a comparatively large effective area and can quickly supply and discharge the compressed air to and from the first pressure chamber 30.

[0028] 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 prevents the compressed air from escaping through a gap between the first cover 18 and the cylinder tube 12. The second outer peripheral seal 66b is positioned within the first opening 70 and disposed between the first main flow path 63 and the first fixed opening 64. The second outer peripheral seal 66b prevents the compressed air from escaping between the first main flow path 63 and the first fixed opening 64.

[0029] 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 displacement of the first cover 18 in the axial direction relative to the cylinder tube 12.

[0030] As in Fig. 1, an end portion of the second cover 20 in the first direction is positioned on a side farther in the second direction than the second fixed opening 78, thereby enabling communication between the second fixed opening 78 and the second pressure chamber 32. The second cover 20 includes an insertion opening 20a, the second damping chamber 72, the second damping seal 74, the second internal flow path 76, and the second fixed opening 78. The insertion opening 20a penetrates a central part of the second cover 20 in the axial direction. The piston rod 16 is inserted through the insertion opening 20a. A rod seal 80 is mounted in a predetermined portion of the insertion opening 20a. The rod seal 80 prevents the compressed air from escaping through a gap between the piston rod 16 and the second cover 20.

[0031] 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 in the first direction and communicates with the second pressure chamber 32. The second damping chamber 72 is positioned at 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.

[0032] 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 damping 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 damping 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 compressed air from the second pressure chamber 32 through the second internal flow path 76.

[0033] The second inner flow path 76 extends in the up / down direction and penetrates the second cover 20 in the diametrical direction. A middle portion of the second inner flow path 76 opens into and communicates with the second damping chamber 72. An upper end portion of the second inner flow path 76 communicates with the second opening 82 via the second main flow path 77. The second inner flow path 76 and the second main flow path 77 have a comparatively large effective area and can quickly supply and discharge compressed air to and from the second pressure chamber 32.

[0034] A third outer peripheral seal 84a and a fourth outer peripheral seal 84b are attached to an outer peripheral part 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. The third outer peripheral seal 84a is arranged between the second main flow path 77 and the second fixed opening 78, preventing air from leaking therebetween. The fourth outer peripheral seal 84b is positioned on one side in the second direction of the second inner flow path 76. The fourth outer peripheral seal 84b prevents compressed air from escaping to the outside of the second cover 20.

[0035] 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 part formed in the cylinder tube 12, and serves to prevent the second cover 20 from being displaced in the axial direction with respect to the cylinder tube 12.

[0036] 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 fixed orifice 64. The first air damping mechanism 22 isolates the first damping chamber 58 from the first pressure chamber 30 through the contact of the first damping protrusion 44 with the first damping seal 60 near the stroke end in the first direction. According to this feature, the first air damping mechanism 22 blocks the communication between the first internal flow path 62 and the first pressure chamber 30. The discharge of the compressed air from the first pressure chamber 30 is via the first fixed orifice 64. The first fixed orifice 64 slows down the speed of the piston 14 by limiting the flow rate of the compressed air.

[0037] As in Fig. 2B and Fig. 4, the second air damping mechanism 24 includes the second damping protrusion 46, the second damping chamber 72, the second damping seal 74, the second internal flow path 76, and the second fixed orifice 78. The second air damping mechanism 24 isolates the second damping chamber 72 from the second pressure chamber 32 through the contact of the second damping protrusion 46 and the second damping seal 74 at the stroke end in the second direction. According to this feature, the second air damping mechanism 24 blocks the communication between the second internal flow path 76 and the second pressure chamber 32. As a result, the compressed air from the second pressure chamber 32 is discharged under throttling through the second fixed orifice 78, and the piston 14 is decelerated.

[0038] The air cylinder 10 is constructed as described above. The operation of the air cylinder 10 is described below.

[0039] 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 fixed port 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 the stroke 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.

[0040] As in Fig. 3, at an intermediate position of the stroke, the first internal flow path 62 and the first fixed orifice 64 communicate with the first pressure chamber 30, and the second internal flow path 76 and the second fixed orifice 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 fixed orifice 78, the piston 14 moves quickly.

[0041] As in Fig. 4, the second cushioning protrusion 46 is inserted into the second cushioning chamber 72 when the piston 14 is displaced in the second direction to the stroke end. 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 through the second fixed orifice 78. The second fixed orifice 78 limits the discharge amount of the compressed air and causes the speed of the piston 14 to be reduced to a range where an impact can be absorbed by a second damper 42.

[0042] 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 fixed port 78 and is supplied to the second pressure chamber 32. According to this feature, the piston 14 performs a stroke in the first direction.

[0043] 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 cushioning seal 60 and the first sealing protrusion 44 abut each other airtight, and the first sealing 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 through the first fixed orifice 64. The first fixed orifice 64 acts to reduce the speed of the piston 14 to a range where an impact can be absorbed by a first damper 40 by limiting the flow amount of the discharged compressed air.

[0044] In the air cylinder 10 described above, the sealing performance of the first damping seal 60 is checked in the following manner. First, the piston 14 is moved to an intermediate position of the Fig. 3. Next, a rubber rod or the like is inserted into the first fixed opening 64 exposed in the first opening 70. This hermetically seals the first fixed opening 64. It should also be noted that the first main flow path 63 is not sealed.

[0045] Next, the piston rod 16 is moved in the first direction. Until it reaches the vicinity of the stroke end in the first direction, the piston 14 moves while the air in the first pressure chamber 30 is discharged through the first main flow path 63.

[0046] Thereafter, when the stroke end is reached, the first cushioning protrusion 44 and the first cushioning seal 60 abut each other. If the sealing performance of the first cushioning seal 60 is normal, the air in the first pressure chamber 30 is not released, and the piston rod 16 and the piston 14 stop before reaching the stroke end.

[0047] On the other hand, when the sealing performance of the first cushion seal 60 is insufficient because the air in the first pressure chamber 30 is discharged through the first internal flow path 62 and the first main flow path 63, the piston rod 16 and the piston 14 move forward toward the stroke end. As mentioned above, the sealing performance of the first cushion seal 60 is checked by checking the stop position of the piston rod 16.

[0048] In addition, when checking the sealing performance of the second cushion seal 74, the second fixed hole 78 is sealed. After that, the piston rod 16 is pulled in the second direction, and it is checked whether the piston rod 16 stops moving in the second direction before reaching the stroke end. If the piston rod 16 stops moving in the second direction before reaching the stroke end, it can be confirmed that the sealing performance of the second cushion seal 74 is normal. If the piston rod 16 can be moved in the second direction up to the stroke end despite the second fixed hole 78 being sealed, it can be confirmed that the sealing performance of the second cushion seal 74 is insufficient.

[0049] As mentioned above, with the air cylinder 10 according to the present embodiment, it is possible to easily and reliably check the sealing performance of the first damping seal 60 or the second damping seal 74. Second embodiment

[0050] As in Fig. 5A, an air cylinder 10A according to a first aspect of the present embodiment differs from the air cylinder 10 described with reference to Fig. 1 to Fig. 4, with regard to the structure of a first cover 18A. In Fig. 5A are the same components as in Fig. 1 to Fig. 4 are designated by the same reference numerals, and a detailed description of these features is omitted.

[0051] The first cover 18A is provided with a damping ring 88 at one end portion on one side in the second direction. The damping ring 88 is an annular member formed of an elastic material. The damping ring 88 dampens by abutting against the piston 14 at the stroke end in the first direction of the piston 14 (see Fig. 1) an impact caused by a collision between the first cover 18A and the piston 14. Since the damping ring 88 has a similar function to the first damper 40 (see Fig. 1), the first damper 40 of the piston 14 in the air cylinder 10A can be omitted.

[0052] The damping ring 88 is positioned on a side further in the axial direction than the first fixed opening 64, which opens into the bottom surface 70a of the first opening 70. Specifically, in the first cover 18A, the damping ring 88, which is a part thereof, has its axial position overlapping with the axial position of the first fixed opening 64. However, the damping ring 88 is spaced diametrically inward from the first fixed opening 64 and does not obstruct the flow of compressed air between the first pressure chamber 30 and the first fixed opening 64.

[0053] The above-described air cylinder 10A has the same advantageous effects as the air cylinder 10 described with reference to Fig. 1 to Fig. 4. Furthermore, in the first aspect of the present embodiment, although the first cover 18A has been described as an example, a similar damping ring 88 may be added to the second cover 20 (see Fig. 1).

[0054] An air cylinder 10B according to a second aspect of the present embodiment, which is shown in Fig. 5B is different from the air cylinder 10 shown with reference to Fig. 1 to Fig. 4, with regard to the structure of a first cover 18B. In Fig. 5B are the same components as in Fig. 1 to Fig. 4 are designated by the same reference numerals, and a detailed description of these features is omitted.

[0055] The first cover 18B is formed thicker in the axial direction than the first cover 18 of the first embodiment. A second-direction end portion of the first cover 18B protrudes further toward one side in the second direction than the first fixed opening 64. Accordingly, in the first cover 18B, the position in its axial direction overlaps the position in the axial direction of the first fixed opening 64.

[0056] The air cylinder 10B includes a communication flow path 90 extending in the axial direction to enable communication between the first fixed opening 64 and the first pressure chamber 30. The communication flow path 90 is formed on an outer peripheral part of the first cover 18B. The communication flow path 90 may have a groove shape extending in the axial direction. Further, the communication flow path 90 may be formed by a reduced-diameter portion extending circumferentially around the entire circumference of the first cover 18B. The cross-sectional area of the communication flow path 90 is larger than the cross-sectional area of the first fixed opening 64. Furthermore, the communication flow path 90 may be formed by cutting the cylinder tube 12 instead of cutting the first cover 18B.

[0057] The above-mentioned air cylinder 10B has the same advantageous effects as the air cylinder 10 described with reference to FIG. Fig. 1 to Fig. 4. Furthermore, in the second aspect of the present embodiment, although the first cover 18B has been described as an example, the second cover 20 (see Fig. 1) be trained in the same way.

[0058] The following supplementary notes are further disclosed with respect to the embodiments described above. Supplementary Note 1

[0059] The air cylinder (10) comprises the cylinder tube (12) with the through-hole (26) extending in the axial direction, the first cover (18) configured to seal the end portion in the first direction of the through-hole, the second cover (20) configured to seal the end portion in the second direction of the through-hole and forming 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 opening (70) formed in the cylinder tube and through which the compressed air can be supplied to and discharged from the first pressure chamber, the first damping chamber (58) formed in the first cover and configured to communicate with the first pressure chamber, the first damping protrusion (44),which is configured to protrude from the piston in the first direction and block the communication between the first damping chamber and the first pressure chamber when inserted into the first damping chamber, the first main flow path (63) configured to communicate with the first damping chamber, and the first fixed opening (64) having an effective area configured to be smaller than the effective area of the first main flow path and configured to open into the first pressure chamber, wherein the first main flow path and the first fixed opening open at a bottom surface (70a) of the first opening.

[0060] The air cylinder described above is capable of easily performing the sealing performance test of the first damping seal by sealing the first fixed opening exposed at the bottom surface of the first opening. Supplementary Note 2

[0061] In the air cylinder according to Supplementary Note 1, the first main flow path may open at the end portion in the first direction of the bottom surface of the first opening, and the first fixed opening may open at the end portion in the second direction of the bottom surface of the first opening. The air cylinder is capable of simplifying the shapes of the first main flow path and the first fixed opening, thereby facilitating their manufacturing. Supplementary Note 3

[0062] In the air cylinder according to Supplementary Note 1 or 2, the second outer peripheral seal (66b) disposed between the first main flow path and the first fixed opening may be attached to the outer peripheral part of the first cover. In such an air cylinder, the second outer peripheral seal can serve a dual function as a seal between the first main flow path and the first fixed opening and as a seal of the first pressure chamber, thereby simplifying the structure. Supplementary Note 4

[0063] In the air cylinder according to any one of Supplementary Notes 1 to 3, the position of the first cover in the axial direction may be offset from the position of the first fixed opening, and the first pressure chamber may extend to the inside of the first fixed opening. In such an air cylinder, the first fixed opening, which opens on the bottom surface of the first opening and is formed by drilling a hole in the diametrical direction, may be directly connected to the first pressure chamber, thereby simplifying the structure and allowing the air cylinder to be downsized. Supplementary Note 5

[0064] In the air cylinder according to any one of Supplementary Notes 1 to 3, the position of the end portion in the axial direction of the first cover may overlap with, or alternatively, coincide with, the position in the axial direction of the first fixed opening. Supplementary Note 6

[0065] In the air cylinder according to any one of Supplementary Notes 1 to 5, the first cover may include the first internal flow path (62) configured to extend in the diametrical direction perpendicular to the axial direction and connect the first damping chamber and the first main flow path, and the axial position of the first internal flow path may overlap with the axial position of the first opening. Such an air cylinder can accommodate the first air damping mechanism and the second air damping mechanism without increasing the axial dimension. Supplementary Note 7

[0066] In the air cylinder according to any one of Supplementary Notes 1 to 6, there may further be provided the second opening (82) formed in the cylinder tube and through which the compressed air can be supplied to and discharged from the second pressure chamber, the second damping chamber (72) formed in the second cover and communicating with the second pressure chamber, the second damping projection (46) formed to protrude from the piston in the second direction and block the communication between the second damping chamber and the second pressure chamber when inserted into the second damping chamber, the second main flow path (77) configured to communicate with the second damping chamber, and the second fixed opening (78) having an effective area configured to be smaller than the effective area of the second main flow path and configured tothat it opens into the second pressure chamber, wherein the second main flow path and the second fixed opening can open at the bottom surface (82a) of the second opening. In addition to being arranged at the stroke end in the first direction, the air cylinder can also be equipped with the first air damping mechanism and the second air damping mechanism at the stroke end in the second direction. 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 in a first direction of the through hole; a second cover (20) configured to seal an end portion 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 can be supplied into 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 damping chamber and the first pressure chamber when inserted into the first damping chamber; a first main flow path (63) configured to communicate with the first damping chamber; and a first fixed opening (64) having an effective area smaller than an effective area of the first main flow path and configured to open into the first pressure chamber; wherein the first main flow path and the first fixed opening open at a bottom surface (70a) of the first opening. [2] The air cylinder according to claim 1, wherein the first main flow path opens at an end portion in the first direction of the bottom surface of the first opening, and the first fixed opening opens at an end portion in the second direction of the bottom surface of the first opening. [3] The air cylinder according to claim 1, wherein a second outer peripheral seal (66b) disposed between the first main flow path and the first fixed opening is attached to an outer peripheral portion of the first cover. [4] The air cylinder according to claim 1, wherein a position in the axial direction of the first cover is offset from a position in the axial direction of the first fixed opening, and the first pressure chamber extends to an inside of the first fixed opening. [5] The air cylinder according to claim 1, wherein a position of an end portion in the axial direction of the first cover overlaps or alternatively coincides with a position in the axial direction of the first fixed opening. [6] Air cylinder according to claim 1, wherein: the first cover includes a first inner flow path (62) configured to extend in a diametrical direction perpendicular to the axial direction and connecting the first damping chamber and the first main flow path; a position in the axial direction of the first inner flow path overlaps with a position in the axial direction of the first opening. [7] Air cylinder according to one of claims 1 to 6, further comprising: a second opening (82) formed in the cylinder tube and through which compressed air can be supplied to and discharged from the second pressure chamber; a second damping chamber (72) formed in the second cover and communicating with the second pressure chamber; a second damping projection (46) configured to protrude from the piston in the second direction and block communication between the second damping chamber and the second pressure chamber when inserted into the second damping chamber; a second main flow path (77) configured to communicate with the second damping chamber; and a second fixed opening (78) having an effective area smaller than an effective area of the second main flow path and configured to open into the second pressure chamber; wherein the second main flow path and the second fixed opening open at a bottom surface (82a) of the second opening.

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