Piston-cylinder device

Abstract

A piston cylinder device according to one embodiment of the present invention may include a cylinder housing having an internal space into which fluid is introduced and including an inlet connected to the internal space; a piston rod having a rod passage, one end of which is located inside the cylinder housing and the other end of which is coupled to an operating member outside the cylinder housing and which transmits fluid to the operating member so that the operating member is operated; and a piston head having a head passage connected to one end of the piston rod, which moves inside the internal space according to hydraulic conditions inside the internal space, one end of which is connected to the rod passage and the other end of which is exposed to the surface.

Description

Technology Field

[0001] The present invention relates to a piston cylinder device, and more specifically to a pneumatic and / or hydraulic cylinder for a valve. Background Technology

[0002] In manufacturing processes across various industries, such as semiconductors, displays, new materials, and aerospace components, process objects are often handled in an atmosphere distinct from the external environment. To provide this atmosphere, chambers are used in various industries to create the environment for the process.

[0003] To create the atmosphere of the chamber, various valve devices, such as gate valves and pendulum valves, are utilized in the chamber. The opening and closing of these valve devices can be implemented by piston cylinder devices connected to the valve devices.

[0004] However, piston cylinder devices, such as pneumatic and hydraulic cylinders, may experience pneumatic and / or hydraulic leakage due to damage to their sealing structures caused by stress concentration resulting from repeated operation. Such leakage hinders the proper operation of valve devices and leads to increased maintenance costs due to repairs and maintenance.

[0005] Meanwhile, when repairing or maintaining valve devices, etc., it is necessary to remove pneumatic and / or hydraulic pressure remaining in the valve device. Therefore, if pneumatic and / or hydraulic pressure inside the valve device is not properly removed through the discharge path installed and connected to the valve device, it is necessary to forcibly remove it. The problem to be solved

[0006] The problem that the present invention aims to solve is to provide a piston cylinder device capable of preventing pneumatic and / or hydraulic leakage to the maximum extent even during long-term use.

[0007] In addition, the problem that the present invention aims to solve is to provide a piston cylinder device capable of forcibly removing pneumatic and / or hydraulic pressure remaining in a valve device.

[0008] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0009] A piston cylinder device according to an embodiment of the present invention for solving the above problem may include: a cylinder housing having an internal space into which fluid is introduced and including an inlet connected to the internal space; a piston rod having a rod passage, one end of which is located inside the cylinder housing and the other end of which is coupled to an operating member outside the cylinder housing and which transmits fluid to the operating member so that the operating member is operated; and a piston head having a head passage connected to one end of the piston rod, which moves inside the internal space according to hydraulic conditions inside the internal space, one end of which is connected to the rod passage and the other end of which is exposed to the surface.

[0010] The above head path can receive fluid through the injection port, with the other end corresponding to the injection port while the piston head is positioned at the injection position in the internal space.

[0011] The other end of the head passage may be located on a side connecting one side of the piston head connected to the piston rod and the other side of the piston head located on the opposite side of the piston rod.

[0012] It may further include a sealing member positioned adjacent to the other end of the head passage to block the gap between the side of the piston head and the inner wall of the cylinder housing, so as to prevent fluid flowing into the head passage through the injection port from being lost into the internal space.

[0013] The sealing member may include a first sealing member that surrounds the side of the piston head and is located on one side of the piston head with respect to the other end of the head passage, and a second sealing member that surrounds the side of the piston head and is located on the rear side of the piston head with respect to the other end of the head passage.

[0014] The above load path may include a first load path for providing a force in one direction to the operating member and a second load path for providing a force in a direction different from the first load path.

[0015] The head path may include a first head path connected to the first load path and a second head path connected to the second load path.

[0016] The above injection port may include a first injection port corresponding to the first head passage when the piston head is positioned at the injection position, and a second injection port corresponding to the second head passage when the piston head is positioned at the injection position.

[0017] The cylinder housing may further include a first head position control passage located in one direction relative to the piston head and delivering fluid into the internal space, and a second head position control passage located in the other direction relative to the piston head and delivering fluid into the internal space.

[0018] To prevent damage to the cylinder housing caused by the force of the piston head being pressed against it, a buffer member disposed between the first head position adjustment passage and the piston head may be further included.

[0019] The cylinder housing may further include a discharge port that corresponds to the other end of the head passage when the piston head is positioned at an injection position and other discharge positions, and through which fluid delivered to the head passage is discharged.

[0020] Other specific details of the present invention are included in the detailed description and drawings. Effects of the invention

[0021] According to embodiments of the present invention, at least the following effects are achieved.

[0022] The cost of maintaining the piston cylinder device can be saved.

[0023] When inspecting the valve unit connected to the piston cylinder unit, problems that may arise from residual pneumatic and / or hydraulic pressure can be prevented.

[0024] The effects according to the present invention are not limited to those exemplified above, and various other effects are included in this specification. Brief explanation of the drawing

[0025] FIG. 1 is a conceptual cross-sectional view of a piston cylinder device in a state where the piston rod is fully accommodated according to one embodiment of the present invention. FIG. 2 is a conceptual cross-sectional view of a piston cylinder device in a state where the piston rod is protruded to the maximum extent according to one embodiment of the present invention. FIG. 3 is a perspective view of a gate valve to which a piston cylinder device according to one embodiment of the present invention is applied. FIG. 4 is an exploded perspective view of a gate valve to which a piston cylinder device according to one embodiment of the present invention is applied. Specific details for implementing the invention

[0026] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0027] Furthermore, the embodiments described herein will be explained with reference to cross-sectional views and / or schematic drawings, which are exemplary illustrations of the present invention. Accordingly, the form of the exemplary drawings may be modified due to manufacturing techniques and / or tolerances, etc. Additionally, in each drawing of the present invention, each component may be depicted slightly enlarged or reduced for convenience of explanation. Throughout the specification, the same reference numerals refer to the same components.

[0028] Hereinafter, the present invention will be described with reference to the drawings for explaining a piston cylinder device according to one embodiment of the present invention.

[0029] For the sake of convenience of explanation, directions such as up, down, left, and right are specified in the following description; however, these directions may be changed depending on the actual use of the invention. Accordingly, the directions mentioned below do not limit the invention and are merely illustrative expressions to complete the disclosure.

[0030] In addition, expressions such as "first," "second," etc. below are added to distinguish between components that are formed identically or similarly, or have identical or similar functions, and the components referred to by expressions such as "first," "second," etc. may be changed as needed.

[0031] FIG. 1 is a conceptual cross-sectional view of a piston cylinder device in a state where the piston rod is fully accommodated according to one embodiment of the present invention. In contrast, FIG. 2 is a conceptual cross-sectional view of a piston cylinder device in a state where the piston rod is fully protruded according to one embodiment of the present invention.

[0032] As illustrated in FIGS. 1 and 2, a piston cylinder device (500) according to one embodiment of the present invention may include a cylinder housing (530), a piston rod (510), and a piston head (520).

[0033] The cylinder housing (530) may be a housing having an internal space (524) into which fluid is introduced. For example, the fluid may be any one of various fluids conventionally used, such as water, hydraulic fluid, or air. This cylinder housing (530) may be formed as an assembly of multiple accessories. The multiple accessories may include a cap housing positioned at the top based on FIGS. 1 and 2, a main housing positioned in the middle, and a base housing positioned at the bottom. A sealing member may be placed between each accessory to prevent fluid loss. The cap housing and the base housing may have a structure for receiving fluid by being connected to an external fluid supply source. Additionally, the main housing may be a cylinder-shaped member having an internal space (524) formed therein.

[0034] A through hole may be formed in the cap housing and the main housing, which is positioned coaxially with the central axis of the cylinder housing (530). A piston rod (510) may be inserted into the through hole. With the piston head (520) positioned in the internal space, the end of the piston rod (510) may be exposed to the outside through the through hole.

[0035] The internal space (524) may be provided as a space formed inside the main housing in the cylinder housing (530). In order for the piston head (520) to move within the internal space (524), the cross-sectional area perpendicular to the height direction of the internal space (524) may be provided to be slightly larger than the upper and lower surface areas of the piston head (520).

[0036] The cylinder housing (530) may be configured to include a first head position adjustment passage (531) and a second head position adjustment passage (533).

[0037] The first head position adjustment passage (531) is located at the top of the cylinder housing (530) and may be a passage communicating with the internal space (524). The first head position adjustment passage (531) may extend from the side of the cap housing and extend to the inner wall of the main housing. Due to the through hole in which the piston rod (510) is positioned, the first head position adjustment passage (531) may be connected at a position deflected to one side with respect to the center of the internal space (524).

[0038] The fluid flowing into the internal space (524) through the first head position control channel (531) can flow into the upper space of the piston head (520) to induce the piston head (520) to move downward. When the piston head (520) moves downward, the fluid located in the lower space of the piston head (520) can be moved to the second head position control channel (533) or discharged through a separate discharge channel.

[0039] The second head position adjustment channel (533) is located at the bottom of the cylinder housing (530) and may be a channel communicating with the internal space (524). The second head position adjustment channel (533) may extend from the side of the base housing to the inner wall of the main housing. The portion of the second head position adjustment channel (533) exposed to the internal space (524) may be aligned coaxially with the central axis of the internal space (524).

[0040] The fluid flowing into the internal space (524) through the second head position control channel (533) flows into the lower space of the piston head (520), thereby inducing the piston head (520) to move upward. When the piston head (520) moves upward, the fluid located in the upper space of the piston head (520) can be moved to the first head position control channel (531) or discharged through a separate discharge channel.

[0041] Meanwhile, the cylinder housing (530) may further include a plurality of inlets (537a, 537b; inlet) and a plurality of outlets (535a, 535b; outlet).

[0042] The inlet ports (537a, 537b) may be formed to selectively supply fluid received from an external fluid source into the internal space (524). To this end, a valve, a pump, etc., may be connected to the inlet ports (537a, 537b) to selectively supply fluid. These inlet ports (537a, 537b) may include a first inlet port (537a) and a second inlet port (537b).

[0043] For example, the first inlet (537a) and the second inlet (537b) may be aligned in the height direction on the upper side of the main housing. The distance between the first inlet (537a) and the second inlet (537b) may correspond to the gap between the first head passage (521) and the second head passage (523) described later.

[0044] The outlets (535a, 535b) may be formed to selectively discharge fluid. The outlets (535a, 535b) may include a first outlet (535a) and a second outlet (535b). The first outlet (535a) and the second outlet (535b) may be aligned in the height direction on the lower side of the main housing. Additionally, the distance between the first outlet (535a) and the second outlet (535b) may correspond to the gap between the first head passage (521) and the second head passage (523).

[0045] The first discharge port (535a) and the second discharge port (535b) may be optionally equipped with a valve, pump, etc. for discharging fluid. Additionally, the first discharge port (535a) and the second discharge port (535b) may normally be blocked with a plug or the connected valve may be locked to prevent fluid from being discharged through the discharge ports (535a, 535b).

[0046] The piston rod (510) is a member extending along the height direction, and a rod passage (511, 513) may extend approximately along the height direction inside. One end of the rod passage (511, 513) may be connected to the head passage (521, 523), and the other end may be exposed to the surface of the other end of the piston rod (510). One end (bottom) of the piston rod (510) may be placed inside the cylinder housing (530) through a through hole of the cylinder housing (530), and the other end (top) may be exposed to the outside of the cylinder housing (530).

[0047] The other end of the piston rod (510) can be coupled to an external operating member. Here, the operating member may be, for example, the gate of a gate valve or the gate of a pendulum valve. The piston rod (510) can perform the opening and closing operation of the gate valve or pendulum valve by utilizing the pressure of the fluid delivered to the rod passage (511, 513). Additionally, the piston rod (510) can be moved axially according to the movement of the piston head (520) to move the coupled operating member.

[0048] The load paths (511, 513) may include a first load path (511) and a second load path (513). The first load path (511) and the second load path (513) may be formed to transmit force in different directions to the operating member. For example, fluid transmitted to the operating member through the first load path (511) may apply a force in one direction to the operating member to induce the gate to close or open. At this time, fluid transmitted to the operating member through the second load path (513) may transmit a force in the opposite direction to the operating member to induce the gate to open or close.

[0049] The piston head (520) is connected to the lower end of the piston rod (510), and its position in the internal space (524) can change depending on the hydraulic conditions inside the internal space (524). More specifically, the upper surface of the piston head (520) can be connected to the lower end of the piston rod (510).

[0050] The piston head (520) is lowered by pressure acting in the upper direction and can be raised by pressure acting in the lower direction. The lowest position of the piston head (520) is shown in FIG. 1, and the highest position is shown in FIG. 2.

[0051] The piston head (520) and the piston rod (510) can be formed by processing a single member. As a result, there may be no joint or connecting parts between the piston head (520) and the piston rod (510). In this case, even with repeated use of the piston head (520) and the piston rod (510), the separation of the piston head (520) and the piston rod (510) or the formation of a gap between the piston head (520) and the piston rod (510) can be prevented as much as possible.

[0052] A head passage (521, 523) extending from a load passage (511, 513) may be formed in the piston head (520). One end of the head passage (521, 523) may be connected to the load passage (511, 513), and the other end may be exposed through the side of the piston head (520). Here, the side may be a surface connecting the upper surface and the lower surface of the piston head (520).

[0053] The head euro (521, 523) may include a first head euro (521) and a second head euro (523). The first head euro (521) is connected to the first load euro (511), and the second head euro (523) may be connected to the second load euro (513).

[0054] The other end of the first head passage (521) and the other end of the second head passage (523) may be aligned along the height direction on the side of the piston head (520). However, this is exemplary, and the other end of the first head passage (521) and the other end of the second head passage (523) may be formed in various positional relationships. A plurality of inlet ports (537a, 537b) and a plurality of outlet ports (535a, 535b) may be formed to correspond to the positional relationship between the other end of the first head passage (521) and the other end of the second head passage (523).

[0055] As a result, when the piston head (520) is at a specific position on the internal space (524), the first head passage (521) and the first injection port (537a) may face each other, and the second head passage (523) and the second injection port (537b) may face each other. The position of the piston head (520) at this time is called the injection position, and in this embodiment, the injection position may be the position when the piston head (520) is raised to its maximum height.

[0056] At the injection location, the head passage (521, 523) and the injection port (537a, 537b) correspond to each other, so that fluid can be delivered to the head passage (521, 523) through the injection port (537a, 537b). The fluid delivered through the first injection port (537a) is delivered to the first load passage (511) through the first head passage (521), and the fluid delivered through the second injection port (537b) can be delivered to the second load passage (513) through the second head passage (523).

[0057] Additionally, when the piston head (520) is at a specific position on the internal space (524), the first head passage (521) and the first outlet (535a) may face each other, and the second head passage (523) and the second outlet (53b) may face each other. The position of the piston head (520) at this time is called the discharge position, and in this embodiment, the discharge position may be the position when the piston head (520) is lowered to its maximum extent.

[0058] At the discharge location, the head passage (521, 523) and the discharge port (535a, 535b) correspond to each other, so that fluid can be discharged through the discharge port (535a, 535b). The fluid delivered to the first load passage (511) passes through the first head passage (521) and is discharged to the first discharge port (535a), and the fluid delivered to the second load passage (513) passes through the second head passage (523) and is discharged to the second discharge port (535b).

[0059] Meanwhile, a piston cylinder device (500) according to one embodiment of the present invention may further include sealing members (522a, 522b, 522c, 522d). The sealing members (522a, 522b, 522c, 522d) may be disposed adjacent to the other end of the head passage (521, 523). The sealing members (522a, 522b, 522c, 522d) may include a first sealing member (522a), a second sealing member (522b), a third sealing member (522c), and a fourth sealing member (522d).

[0060] Each sealing member (522a, 522b, 522c, 522d) is configured to surround the side of the piston head (520) and can be arranged along the perimeter of the side of the piston head (520). Additionally, the sealing members (522a, 522b, 522c, 522d) are formed of an elastic material and may have a thickness greater than the gap between the piston head (520) and the inner wall of the cylinder housing (530). As a result, when the sealing members (522a, 522b, 522c, 522d) are arranged, the space above and the space below the sealing members (522a, 522b, 522c, 522d) can be prevented from fluidly communicating with each other. For example, the sealing members (522a, 522b, 522c, 522d) may be provided as O-rings.

[0061] By means of a plurality of sealing members (522a, 522b, 522c, 522d), fluid flowing into the internal space (524) through the first head position control channel (531) can be prevented from flowing into the space below the piston head (520). Additionally, fluid flowing into the internal space (524) through the second head position control channel (533) can be prevented from flowing into the space above the piston head (520). Since the fluid located above and the fluid located below the piston head (520) are not mixed with each other by means of a plurality of sealing members (522a, 522b, 522c, 522d), the piston head (520) can be moved appropriately using the pressure difference between the upper and lower sides.

[0062] The first sealing member (522a) and the second sealing member (522b) may be positioned with the other end of the first head passage (521) in between. More specifically, the first sealing member (522a) may be positioned above the other end of the first head passage (521) so as to be adjacent to the upper surface of the piston head (520) with respect to the other end of the first head passage (521). Additionally, the second sealing member (522b) may be positioned below the other end of the first head passage (521) so as to be adjacent to the lower surface of the piston head (520) with respect to the other end of the first head passage (521).

[0063] Due to the presence of the first sealing member (522a) and the second sealing member (522b), fluid flowing into or discharged from the first head passage (521) at the injection or discharge position can be prevented from being lost into the internal space (524).

[0064] In addition, due to the presence of the first sealing member (522a) and the second sealing member (522b), fluid flowing into or discharged from the first head passage (521) at the injection position or discharge position can be prevented from moving to the second head passage (523).

[0065] The third sealing member (522c) and the fourth sealing member (522d) may be positioned with respect to the other end of the second head passage (523). More specifically, the third sealing member (522c) may be positioned above the other end of the second head passage (523) so as to be adjacent to the upper surface of the piston head (520) with respect to the other end of the second head passage (523). Additionally, the fourth sealing member (522d) may be positioned below the other end of the second head passage (523) so as to be adjacent to the lower surface of the piston head (520) with respect to the other end of the second head passage (523).

[0066] Due to the presence of the third sealing member (522c) and the fourth sealing member (522d), fluid flowing into or discharged from the second head passage (523) at the injection or discharge position can be prevented from being lost into the internal space (524).

[0067] In addition, due to the presence of the third sealing member (522c) and the fourth sealing member (522d), fluid flowing into or discharged from the second head passage (523) at the injection or discharge position can be prevented from moving toward the first head passage (521).

[0068] Meanwhile, a piston cylinder device (500) according to one embodiment of the present invention may include a cushioning member (532, 534). The cushioning member (532, 534) can prevent the cylinder housing (530) from being damaged by the force of the piston head (520) being pressed against it. Such cushioning member (532, 534) may be formed of an elastic material.

[0069] The buffer member (532, 534) may include a first buffer member (532) mounted on the inner wall of the cylinder housing (530) so as to face the upper surface of the piston head (520). The first buffer member (532) may be formed to resemble the shape of the ceiling of the internal space (524) and may be positioned on the ceiling side of the internal space (524). Additionally, a hole may be formed through the first buffer member (532) that is aligned with a through hole and a first head position adjustment channel (531).

[0070] The buffer members (532, 534) may include a second buffer member (534) mounted on the inner wall of the cylinder housing (530) so as to face the bottom surface of the piston head (520). The second buffer member (534) may be formed to resemble the shape of the bottom of the internal space (524) and may be positioned on the bottom side of the internal space (524). A hole may be formed through the second buffer member (534) that aligns with the second head position adjustment channel (533).

[0071] Due to the cushioning members (532, 534), the impact received by the cylinder housing (530) by the movement of the piston head (520) is reduced, so the service life of the cylinder housing (530) can be extended. In addition, the user can extend the service life of the piston cylinder device (500) with relatively low maintenance costs by replacing the cushioning members (532, 534) at appropriate times.

[0072] Hereinafter, based on the above description, an example of use of a piston cylinder device (500) according to an embodiment of the present invention is described. More specifically, with reference to FIGS. 3 and 4, an exemplary case in which a piston cylinder device (500) according to an embodiment of the present invention is used in a gate valve is described below.

[0073] FIG. 3 is a perspective view of a gate valve to which a piston cylinder device according to one embodiment of the present invention is applied. In contrast, FIG. 4 is an exploded perspective view of a gate valve to which a piston cylinder device according to one embodiment of the present invention is applied.

[0074] As illustrated in FIGS. 3 and 4, a plurality of piston cylinder devices (500, 600) according to one embodiment of the present invention may be mounted on a single gate valve (100). Since the piston cylinder devices (500, 600) according to one embodiment of the present invention have been described with reference to FIGS. 1 and 2, a redundant description is omitted.

[0075] The gate valve (100) may include two piston cylinder devices (500, 600), a valve body (200), a gate (300), and an opening / closing cylinder (400).

[0076] The valve body (200) may be provided in the shape of an enclosure in which the upper and lower parts are opened and closed by an upper plate (210) and a lower plate (220). A pair of openings (230) communicating to the front and rear may be formed in the valve body (200). Of course, a first sealing member (211) and a second sealing member (221) may be installed between the upper plate (210) and the upper surface of the valve body (200) and between the lower plate (220) and the lower surface of the valve body (200) to maintain airtightness inside the valve body (200).

[0077] Additionally, as the valve body (200) is positioned between vacuum chambers (not shown), a third sealing member (231) that surrounds the rim of the opening (230) may be installed on the front and rear of the valve body (200) respectively to maintain airtightness between the valve body (200) and the vacuum chambers (not shown).

[0078] The gate (300) may have an area larger than the opening (230) corresponding to the opening (230) formed in the valve body (200). The gate (300) may be positioned inside the valve body (200). Of course, a fourth sealing member (310) may be installed on one side of the gate (300) facing the valve body (200) to maintain airtightness between the gate (300) and the valve body (200).

[0079] The opening / closing cylinder (400) is positioned inside the valve body (200) and behind the gate (300). The opening / closing cylinder (400) drives the gate (300) forward and backward toward the opening (230). Since the internal configuration of the opening / closing cylinder (400) is a known technology already widely known in the field of technology, a detailed description of the configuration will be omitted.

[0080] The gate (300) is supported by an opening / closing cylinder (400) and can open / close an opening (230) formed in the valve body (200) according to the reciprocating drive of the opening / closing cylinder (400). The number of such opening / closing cylinders (400) can be increased or decreased by considering the size of the gate (300), the individual output of the opening / closing cylinders (400), etc.

[0081] Meanwhile, the gate valve (100) allows for the exchange or entry / exit of a substrate between vacuum chambers (not shown) only when the gate (300) is completely removed from the passage of the mutually connected opening (230) along with the reciprocating drive of the gate (300) by the opening / closing cylinder (400). Therefore, the gate valve (100) must be configured to be able to raise and lower the opening / closing cylinder (400) that supports the gate (300). To this end, a plurality of piston cylinder devices (500, 600) can jointly support a support frame (700) on which the opening / closing cylinder (400) is mounted.

[0082] A pair of lifting blocks (560, 660) are positioned on both sides of the support frame (700), and each of the pair of lifting blocks (560, 660) can be connected to a piston rod (510; see FIGS. 1 and 2) of any one of the piston cylinder devices (500, 600).

[0083] Accordingly, the support frame (700) can be raised by the raising of the piston rod (510), and the height of the gate (300) can be adjusted by the raising of the support frame (700). After the gate (300) is received as much as possible inside the valve body (200) (open state), if the piston rod (210) is received as much as possible inside the cylinder housing (530), the gate (300) can be lowered as much as possible and completely removed from the passage.

[0084] Meanwhile, within each lifting block (550, 660), passages may be formed that are connected to the first load passage (511) and the second load passage (513), respectively, and ultimately deliver fluid to the opening / closing cylinder (400).

[0085] For example, when fluid is supplied to the first load channel (511) through the first inlet (537a), the fluid can be transferred from the first load channel (511) to the lifting block (560, 660). The lifting block (560, 660) can transfer the fluid received from the first load channel (511) to the opening / closing cylinder (400) to operate the gate (300) in an opening or closing direction.

[0086] Similarly, when fluid is supplied to the second load channel (513) through the second injection port (537b), fluid is supplied to the opening / closing cylinder (400) through the lifting block (560, 660), so that the gate (300) can move in the opposite way to when fluid is supplied to the first load channel (511).

[0087] When performing maintenance on the gate valve (100), the gate (300) is completely removed from the passage and initialized as described above, and then the maintenance work is performed. At this time, depending on the case, fluid may remain inside the opening / closing cylinder (400), making it difficult to return the gate (300) to its initial state.

[0088] At this time, the user can move the cylinder housing (530) of the piston cylinder device (500, 600) according to one embodiment of the present invention toward the valve body (200) to induce the piston head (520) to move to the discharge position, and then use the discharge port (535a, 535b) to forcibly discharge the fluid remaining in the opening / closing cylinder (400).

[0089] Accordingly, when a piston cylinder device (500, 600) according to one embodiment of the present invention is applied to a gate valve (100), it has the advantage of being able to initialize the gate valve (100) even when pneumatic or hydraulic pressure remains in the opening / closing cylinder (400).

[0090] A person skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0091] 100: Gate valve 200: Valve body 300: Gate 400: Opening / closing cylinder 500, 600: Piston cylinder device 510: Piston rod 520: Piston head 524: Internal space 530: Cylinder housing 531: First head position adjustment passage 532, 534: Buffer members 533: Second head position adjustment passage 535a, 535b: Discharge port 537a, 537b: Injection port

Claims

Claim 1 A piston cylinder device comprising: a cylinder housing having an internal space into which fluid is introduced and including an inlet connected to the internal space; a piston rod having one end located inside the cylinder housing and the other end coupled to an operating member outside the cylinder housing, and including a rod passage that transmits fluid to the operating member so that the operating member is operated; and a piston head connected to one end of the piston rod, which moves inside the internal space according to hydraulic conditions inside the internal space, and having a head passage formed with one end connected to the rod passage; wherein the other end of the head passage is exposed to the outside from the side of the piston head, and when the piston head is positioned at an injection position on the internal space, the other end corresponds to the inlet and receives fluid through the inlet. Claim 2 A piston cylinder device according to claim 1, wherein the other end of the head passage is located on a side connecting one side of the piston head connected to the piston rod and the back side of the piston head located on the opposite side of the piston rod. Claim 3 A piston cylinder device according to claim 2, further comprising a sealing member disposed adjacent to the other end of the head passage to block the gap between the side of the piston head and the inner wall of the cylinder housing, so as to prevent fluid flowing into the head passage through the inlet from being lost into the internal space. Claim 4 A piston cylinder device according to claim 3, wherein the sealing member comprises: a first sealing member that surrounds the side of the piston head and is located on one side of the piston head with respect to the other end of the head passage; and a second sealing member that surrounds the side of the piston head and is located on the rear side of the piston head with respect to the other end of the head passage. Claim 5 A piston cylinder device according to claim 1, wherein the load path comprises a first load path for providing a force in one direction to the operating member and a second load path for providing a force in a direction different from the first load path, the head path comprises a first head path connected to the first load path and a second head path connected to the second load path, and the injection port comprises a first injection port corresponding to the first head path when the piston head is positioned at the injection position and a second injection port corresponding to the second head path when the piston head is positioned at the injection position. Claim 6 A piston cylinder device according to claim 1, wherein the cylinder housing further comprises: a first head position control passage located in one direction relative to the piston head and delivering fluid into the internal space; and a second head position control passage located in the other direction relative to the piston head and delivering fluid into the internal space. Claim 7 A piston cylinder device according to claim 6, further comprising a buffer member disposed between the first head position adjustment passage and the piston head to prevent damage to the cylinder housing by the force of the piston head being pressed against it. Claim 8 A piston cylinder device according to claim 1, wherein the cylinder housing further comprises a discharge port through which fluid delivered to the head passage is discharged, the cylinder housing corresponds to the other end of the head passage when the piston head is positioned at a discharge position different from the injection position.

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