Loss-prevention manhole cover device

Abstract

The present invention relates to a loss-prevention type manhole cover device that automatically locks and unlocks a manhole cover in conjunction with the backflow state and backflow release state (or normal conditions) of rainwater during rain or flood, thereby allowing for normal manhole maintenance during normal conditions and preventing the loss of the manhole cover during rainwater backflow, thereby preventing safety accidents such as casualties caused by the loss of the manhole cover. According to the present invention, a loss-prevention type manhole cover device is provided, characterized by comprising: a ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover, configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure.

Description

Technology Field

[0001] The present invention relates to a loss-prevention type manhole cover device, and more specifically, to a loss-prevention type manhole cover device that automatically locks and unlocks the manhole cover in conjunction with the backflow state and backflow release state (or normal state) of rainwater during rain or flood, thereby allowing for normal manhole maintenance during normal times and preventing the loss of the manhole cover during rainwater backflow, thereby preventing safety accidents such as casualties caused by the loss of the manhole cover. Background Technology

[0003] Generally, gas pipes, water and sewage pipes, communication cables, and high-voltage cables are usually buried underground because if exposed above ground or in the air, the risk of damage or various safety accidents increases due to environmental conditions such as rain or strong winds, or contact with other objects.

[0004] Manholes are typically installed at regular intervals along these gas pipes or water and sewage pipes.

[0005] FIG. 1 is a cross-sectional view showing a conventional manhole, which is composed of a manhole base (1) fixedly installed at the entrance of an underground drainage chamber and a manhole cover (2) that opens and closes the entrance of the manhole base (1) and has a ventilation hole (3) formed therein, and the manhole cover (2) has a structure in which it is installed on a seating ledge formed within the manhole base (1).

[0006] In the event that rainwater backflow occurs during rainfall, the manhole cover of a rainwater manhole installed in a rainwater drainage channel separates or detaches from the seating ledge of the manhole base due to the backflow.

[0007] If the manhole cover separates or detaches from the manhole base due to backflow as described above, the following problems occur.

[0008] First, economic loss occurs as the manhole cover is lost due to separation or detachment from the manhole base.

[0009] Second, if the manhole cover is detached or dislodged from the manhole base, the manhole is left open, leading to safety accidents such as fatal falls.

[0010] To resolve this problem, personnel should immediately reinstall the detached manhole covers onto the manhole supports once the backflow caused by flooding is cleared; however, due to a shortage of manpower, the detached manhole covers are currently unable to be returned to their original positions.

[0011] Furthermore, due to global warming, sudden heavy rainfall is becoming increasingly frequent, and the amount of rain falling during these sudden downpours is also increasing significantly.

[0012] Therefore, due to such sudden heavy rain, backflow inevitably occurs in conventionally constructed rainwater drainage channels. Although multiple through holes (3) are formed in the manhole cover (2) as shown in Fig. 2 to allow rainwater to flow in, this does not address the problem of the manhole cover being lost due to backflow caused by sudden heavy rain. Furthermore, even if the manhole is not lost due to backflow caused by rainwater, there is a possibility that it may be separated by a third party other than the manager or by external force.

[0013] As part of an effort to address this, Korean Registered Patent Publication No. 10-2559153 discloses "a manhole cover for preventing loss during manhole backflow and a manhole operation management system using the same."

[0014] Korean Registered Patent Publication No. 10-2559153 discloses a structure in which a protrusion (122) is provided on the lower part of the upper circular cover (121) of a manhole cover (120) and a groove (110a) is provided on the side of a frame (100a) into which the protrusion (122) can be inserted in one direction, so that when the manhole cover (120) is lowered (closed), it is rotated sideways so that the protrusion (122) on the lower part of the upper circular cover (121) is inserted into the groove (110a) on the side of the frame (100a) and secured.

[0015] However, Korean Registered Patent Publication No. 10-2559153 is connected to the protrusion (122) of the upper circular cover (121) and the groove (110a) of the frame (100a) and is always in a locked state, so there is the inconvenience of having to release the connection state for normal work, and in particular, there is a problem that it is difficult to easily release the connection if foreign matter gets stuck in the connection part.

[0016] In addition, there is still a problem in that if either the protrusion (122) of the upper circular cover (121) or the groove (110a) of the frame (100a) is damaged, the upper circular cover is easily opened and lost due to backflow water pressure. Prior art literature

[0018] Republic of Korea Registered Patent Publication No. 10-2559153 (Published July 25, 2023) Republic of Korea Registered Patent Publication No. 10-1491956 (Published February 11, 2015) Republic of Korea Registered Patent Publication No. 10-2310030 (Published October 7, 2021) Republic of Korea Registered Patent Publication No. 10-1463233 (Published November 26, 2014) Republic of Korea Published Patent Publication No. 10-2013-0002512 (Published January 8, 2013) The problem to be solved

[0019] Accordingly, the present invention, which aims to solve the aforementioned conventional problems, is intended to provide a loss-prevention type manhole cover device that automatically locks and unlocks the manhole cover in conjunction with the backflow state and backflow release state (or normal state) of rainwater during rain or flood, thereby allowing for normal manhole management during normal times and preventing the loss of the manhole cover during backflow, thereby preventing safety accidents such as casualties caused by the loss of the manhole cover.

[0020] In addition, another objective of the present invention is to provide a loss-prevention manhole cover device capable of immediately notifying of the loss of a manhole cover simultaneously with the loss of the manhole cover when the manhole cover is lost due to the backflow of rainwater.

[0021] In addition, another objective of the present invention is to provide a loss-prevention type manhole cover device that prevents incomplete fixation or loss of the manhole cover by preventing opening by external force or arbitrary opening by maintaining the manhole cover in an arbitrarily locked state and allowing the manhole cover to be opened only by an opening operation by a worker.

[0022] The problems solved by 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

[0024] According to one aspect of the present invention for achieving the above objectives and other features of the present invention, a loss-prevention manhole cover device is provided, characterized by comprising: a ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover and configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure.

[0025] In the present invention, the ring-shaped support member is formed as a ring-shaped member with a cross-section of 'T' or a cross-section of 'L', and the manhole cover locking-unlocking unit may include a rotational force generating means configured to generate rotational force by hydraulic pressure, which is coupled to the manhole cover at the bottom of the manhole cover, and an automatic locking-unlocking means configured to lock the manhole cover to the ring-shaped support member when hydraulic pressure is applied, and to automatically unlock the locking state when hydraulic pressure is released.

[0026] In the present invention, the rotational force generating means may include an extension rod extending downward from the center of the lower surface of the manhole cover; and a rotational force generating member coupled to the extended end of the extension rod and generating rotational force through hydraulic action.

[0027] The above rotational force generating means may include a rotational force generating member that is integrally formed on the lower surface of the manhole cover and generates rotational force through hydraulic pressure.

[0028] In the present invention, the rotational force generating member may be composed of a plurality of twist blades formed with spacing in the circumferential direction and formed by twisting so as to gradually increase or decrease from the center to the outer edge.

[0029] In the present invention, the automatic locking-unlocking means comprises a projection formed on one of the inner edge of the ring-shaped support member and the outer edge of the manhole cover, and a coupling groove formed on the other of the inner edge of the ring-shaped support member and the outer edge of the manhole cover, wherein when the manhole cover is seated on the ring-shaped support member, the projection is mounted in the longitudinal direction and when rotational force is generated by the rotational force generating means, the projection moves to one side to restrain the upward movement of the manhole cover, and when the hydraulic pressure is released, the projection moves to its original position. The coupling groove may include a vertical mounting groove portion in which the upper end is open upward and the lower end is closed, and a restraining groove portion formed at the lower end of the vertical mounting groove portion with an upward slope in the circumferential direction.

[0030] In the present invention, the manhole cover further includes a constant fixing maintenance means configured to maintain a constant fixed state with respect to the ring-shaped support member, wherein the constant fixing maintenance means may include a fixing maintenance groove extending horizontally from the extended end of the restraining groove, a jig coupling groove formed symmetrically on the upper edge of the manhole cover, and an operating jig coupled to the jig coupling groove to rotate the manhole cover.

[0031] In the present invention, the manhole cover locking-unlocking unit comprises a link, one end of which is rotatably coupled to the lower surface of the manhole cover, and a buoyancy member coupled to the other end of the link, and the length of the link may be formed to be larger than the inner diameter of the ring-shaped support member.

[0032] In the present invention, the manhole cover further includes a constant fixing maintenance means configured to be constantly fixed to the ring-shaped support member, wherein the constant fixing maintenance means includes a fixed rod member having one end exposed to the outside through the manhole cover and the other end rotatably coupled to the other end of the link, and a locking projection formed protruding from the inner edge of the ring-shaped mounting portion of the ring-shaped support member, wherein the fixed rod member is formed with an L-shaped head portion at the upper end and a ring is provided at the upper end of the head portion, wherein the manhole cover has a seating groove formed on one side for the head portion to be seated and a fixed seating groove formed on the other side in the rotational direction, and the bottom surface of the fixed seating groove may be formed higher than the height of the bottom surface of the seating groove.

[0033] In the present invention, the manhole cover locking-unlocking unit comprises a plurality of guide rails spaced radially apart on the lower surface of the manhole cover, a sliding member movable back and forth along the guide rails, a moving force generating means configured to drive the sliding member back and forth in conjunction with water pressure, and a locking groove formed in the ring-shaped support member into which the end of the sliding member advancing by the moving force generating means is inserted. The moving force generating means comprises a connecting link, one end of which is rotatably coupled to the other end of the sliding member, a vertical movement rod member, the other end of which is rotatably coupled while inclined downward, and a buoyancy member provided at the lower end of the vertical movement rod member. The other end of the connecting link may be coupled to the vertical movement rod member while in an inclined downward state.

[0034] In the present invention, the manhole cover further comprises a constant fixing maintenance means configured to be constantly fixed to the ring-shaped support member, wherein the constant fixing maintenance means is configured such that one end penetrates the manhole cover and is exposed to the outside, and the other end is configured as a fixed rod member coupled to the upper end of the vertically moving rod member, wherein the fixed rod member is formed with an L-shaped head portion at the upper end and a ring is provided at the upper end of the head portion, wherein the manhole cover has a seating groove formed on one side for the head portion to be seated, and a fixed seating groove formed on the other side in the rotational direction, and the bottom surface of the fixed seating groove may be formed higher than the height of the bottom surface of the seating groove.

[0035] In the present invention, the invention further comprises an automatic expansion means detachably coupled to the lower surface of the manhole cover and configured to automatically expand when the manhole cover is detached from a ring-shaped support member by a certain distance or more, and a connecting cable having one end coupled to the ring-shaped support member and the other end coupled to the automatic expansion means. The automatic expansion means may include an expansion chamber formed of an expandable material and detachably provided on the lower surface of the manhole cover in a contracted state, a compressed air cylinder provided on one side of the expansion chamber, and an expansion trigger that detaches together with the manhole cover when the manhole cover is detached, thereby opening the compressed air cylinder to inject compressed air into the expansion chamber. Effects of the invention

[0037] The loss-prevention type manhole cover device according to the present invention provides the following effects.

[0038] First, the present invention has the effect of preventing safety accidents caused by the loss of manhole covers by reliably preventing the manhole covers from being lost due to backflowing rainwater during rainy weather.

[0039] Second, the present invention has the effect of ensuring functionality and usability by automatically locking and unlocking the manhole cover in conjunction with the backflow state and the backflow release state (or normal state), thereby allowing for normal manhole management during normal times and preventing the loss of the manhole cover during backflow, thereby preventing accidents such as loss of manhole cover.

[0040] Third, the present invention has the effect of enabling immediate notification of the loss of a manhole cover simultaneously with the loss of the manhole cover when the manhole cover is lost due to the backflow of rainwater, thereby visually indicating the location of the loss to prepare for safety accidents, and allowing the loss point to be easily identified and promptly addressed in the future.

[0041] Fourth, the present invention has the effect of preventing safety accidents more reliably by covering the manhole opening through an auxiliary cover member and / or notifying simultaneously with the loss of the manhole cover.

[0042] Fifth, the present invention has the effect of preventing incomplete fixation or loss of the manhole cover by preventing opening by external force or arbitrary opening by maintaining the manhole cover in a locked state and allowing the manhole cover to be opened only by an opening operation by a worker.

[0043] The effects of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0045] Figure 1 is a cross-sectional view showing a conventional manhole. FIG. 2 is a schematic diagram showing a loss-prevention type manhole cover device according to a first embodiment of the present invention. FIG. 3 is a drawing showing embodiments of a rotational force generating means of a manhole cover locking-unlocking unit included in a loss-prevention type manhole cover device according to the first embodiment of the present invention. FIG. 4 is a diagram showing an unfolded automatic locking-unlocking means of a manhole cover locking-unlocking unit included in a loss-prevention type manhole cover device according to the first embodiment of the present invention. FIG. 5 is a drawing showing an example of a water pressure induction means included in a loss-prevention type manhole cover device according to the first embodiment of the present invention. FIG. 6 is a drawing showing an embodiment of a permanent fixing means included in a loss-prevention type manhole cover device according to the first embodiment of the present invention. FIG. 7 is a schematic diagram showing a loss-prevention type manhole cover device according to a second embodiment of the present invention. FIG. 8 is a drawing showing a manhole cover locking-unlocking unit included in a loss-prevention type manhole cover device according to a second embodiment of the present invention. FIG. 9 is a drawing showing a loss-prevention type manhole cover device according to a third embodiment of the present invention. FIG. 20 is a drawing showing an automatic expansion means included in a loss-prevention type manhole cover device according to the present invention. FIG. 11 is a drawing showing a manhole closing auxiliary means included in a loss-prevention type manhole cover device according to the present invention. Specific details for implementing the invention

[0046] Further objects, features, and advantages of the present invention can be more clearly understood from the following detailed description and the accompanying drawings.

[0047] Before providing a detailed description of the present invention, it should be understood that the present invention is capable of various modifications and may have various embodiments, and that the examples described below and illustrated in the drawings are not intended to limit the present invention to specific embodiments, but rather include all modifications, equivalents, and substitutions that fall within the spirit and scope of the present invention.

[0048] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0049] The terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0050] Additionally, terms such as "...part," "...unit," and "...module" as described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0051] Furthermore, in the description referring to the attached drawings, identical components are assigned the same reference numeral regardless of drawing symbols, and redundant descriptions thereof are omitted. In describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0052] The loss-prevention manhole cover device according to the present invention is configured with a component in the manhole cover that automatically locks or unlocks the manhole cover in conjunction with a rainwater backflow state (water pressure action) or a backflow release state (release of water pressure action) caused by heavy rainfall, etc., thereby preventing the manhole cover from being lost from the manhole during rainwater backflow and maintaining a normal manhole state during normal times. Furthermore, in the event that the manhole cover is lost, the device is equipped with a component that notifies of the loss of the manhole cover and / or auxiliaryly covers the manhole opening, thereby enabling a supplementary response to the manhole loss state. Additionally, the device may be configured to allow a worker to manually operate the device to maintain a constantly locked state.

[0053] Hereinafter, a loss-prevention type manhole cover device according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

[0054] First, a loss-prevention type manhole cover device according to the first embodiment of the present invention will be described.

[0055] FIG. 2 is a schematic diagram showing a loss-prevention type manhole cover device according to a first embodiment of the present invention, FIG. 3 is a diagram showing embodiments of a rotational force generating means of a manhole cover locking-unlocking unit included in a loss-prevention type manhole cover device according to a first embodiment of the present invention, FIG. 4 is a diagram showing an unfolded automatic locking-unlocking means of a manhole cover locking-unlocking unit included in a loss-prevention type manhole cover device according to a first embodiment of the present invention. FIG. 5 is a diagram showing an embodiment of a water pressure induction means included in a loss-prevention type manhole cover device according to a first embodiment of the present invention, FIG. 6 is a diagram showing an embodiment of a constant fixed maintenance means included in a loss-prevention type manhole cover device according to a first embodiment of the present invention.

[0056] As shown in FIGS. 2 to 6, the loss-prevention type manhole cover device according to the first embodiment of the present invention comprises a ring-shaped support member (110), a manhole cover (120), and a manhole cover locking-unlocking unit (200), and may additionally include a constant fixing maintenance means (250).

[0057] Specifically, the loss-prevention type manhole cover device according to the first embodiment of the present invention comprises, as shown in FIGS. 2 to 6, a ring-shaped support member (110) provided at the opening of a manhole (a manhole entrance where a manhole cover is to be installed); a manhole cover (120) detachably provided at the central opening of the ring-shaped support member (110) to cover the opening of the manhole; and a manhole cover locking-unlocking unit (200) provided between the ring-shaped support member (110) and the manhole cover (120) configured so that the manhole cover (120) is automatically locked and unlocked to the ring-shaped support member (110) by means of a rainwater backflow state (water pressure action state) or a backflow release state (water pressure release state). In addition, the loss-prevention type manhole cover device according to the first embodiment of the present invention may further include a constant fixation maintenance means (250) configured to be included in the manhole cover locking-unlocking unit (200) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0058] The ring-shaped support member (110) has an outer edge formed in a shape corresponding to the opening shape of a manhole, and an inner opening formed in a shape corresponding to the shape of a manhole cover (120).

[0059] In one embodiment, the ring-shaped support member (110) may be composed of a ring-shaped member with a cross-section in the shape of a 'T', an inverted 'T', or an 'L'. Specifically, the ring-shaped support member (110) may include a ring-shaped mounting part (111) formed in a shape corresponding to a manhole entrance, and a ring-shaped wall part (112) protruding upward from the center of the upper surface of the ring-shaped mounting part (111).

[0060] The ring-shaped support member (110) formed in this manner is formed with a stepped portion at each of the upper outer portion and the upper inner portion. At the outer stepped portion, the ring-shaped support member (110) is mounted on the ground at the entrance of the manhole, and its upper surface forms a flat plane with the road surface, and is embedded in asphalt concrete or asphalt concrete, etc., thereby being completely fixed to the road surface. And a manhole cover (120) is seated on the inner stepped portion.

[0061] The above ring-shaped support member (110) is provided with a component of a manhole cover locking-unlocking unit (200), which will be described in detail below in conjunction with a manhole cover (120).

[0062] The above ring-shaped support member (110) is made of a metal material and can be formed in the shape of a circular ring or a polygonal ring including a square.

[0063] Furthermore, the manhole cover (120) is a component configured to open and close the opening of the ring-shaped support member (100).

[0064] The above manhole cover (120) is formed so that both edges rest on a stepped portion formed on the inner side of the ring-shaped support member (110), and is formed to cover the central opening of the ring-shaped support member (110).

[0065] In the drawing, the manhole cover (120) is shown as having a lower portion formed in two steps corresponding to the inner shape of the ring-shaped support member (110), but the manhole cover (120) may have a predetermined thickness and may be formed as a circular plate-shaped body with an outer diameter corresponding to the inner diameter of the ring-shaped wall portion (112).

[0066] The above manhole cover (120) is also provided with another component of the manhole cover locking-unlocking unit (200), which will be described in detail below, in conjunction with the above ring-shaped support member (110).

[0067] Next, the manhole cover locking-unlocking unit (200) is configured to be provided between the ring-shaped support member (110) and the manhole cover (120) so that the manhole cover (120) is automatically locked and unlocked to the ring-shaped support member (110) by means of a backflow state (water pressure action state) or a backflow release state (water pressure action release state).

[0068] As shown in FIGS. 3 and 4, the above manhole cover locking-unlocking unit (200) is provided at the bottom of the manhole cover (120) and includes a rotational force generating means (210) configured to generate rotational force using the force of backflowing rainwater, i.e., water pressure, so that the manhole cover (120) rotates, and an automatic locking-unlocking means (220) configured to be provided between the opposing surfaces of the ring-shaped support member (110) and the manhole cover (120), specifically between the inner edge of the ring-shaped wall portion (112) of the ring-shaped support member (110) and the outer edge of the manhole cover (120), so that the manhole cover (120) receives the rotational force from the rotational force generating means (210) and locks to the ring-shaped support member (110), and automatically unlocks when the water pressure action is released.

[0069] The above rotational force generating means (210) includes an extension rod (211) extending downward from the center of the lower surface of the manhole cover (120), and a rotational force generating member (212) in which the end of the extension rod (211) is connected to the center of the upper surface and generates rotational force through hydraulic action.

[0070] The above-mentioned rotational force generating member (212) may be composed of a twist blade that extends radially around a central rotation axis as shown in (A) of FIG. 3 and is formed by twisting from the root portion (i.e., center) to the tip portion (i.e., edge).

[0071] The above twist blade may be formed with a predetermined twist angle (e.g., 5° to 45°) that gradually increases or decreases from the center to the outer edge. For example, the root portion may be formed to have an angle of attack of 30° and the tip portion to have an angle of attack of 5°.

[0072] Here, the rotational force generating member (212) may be configured such that the extension rod (211) is omitted and the rotational force generating member (212) is directly provided on the lower surface of the manhole cover (120), as shown in (B) of FIG. 3.

[0073] Furthermore, the automatic locking-unlocking means (220) is provided between the opposing surfaces of the ring-shaped support member (110) and the manhole cover (120), specifically between the inner edge of the ring-shaped wall portion (112) of the ring-shaped support member (110) and the outer edge of the manhole cover (120), so that the manhole cover (120), which receives the rotational force of the rotational force generating means (210), is locked to the ring-shaped support member (110), and is configured so that the locking state is automatically released when the hydraulic pressure is released.

[0074] Specifically, the automatic locking-unlocking means (220) is configured such that when the manhole cover (120) is seated on the ring-shaped support member (110), the projection (221) is formed on one of the inner edge of the ring-shaped wall (112) of the ring-shaped support member (110) and the outer edge of the manhole cover (120), and when the manhole cover (120) is seated on the ring-shaped support member (110), the projection (221) is mounted in the longitudinal direction, and when rotational force is generated by the rotational force generating means (210), the projection (221) moves to one side to restrain the upward movement of the manhole cover (120), and in the state where the hydraulic pressure action is released, the projection (221) is configured to be in a position where it can be moved upward (i.e., the initial mounting position where it can be separated from the ring-shaped support member (110). It includes a coupling groove (222).

[0075] The above-mentioned protrusion (221) may be formed as a square protrusion with a lower surface inclined from one side to the other, or as a hemispherical (dome-shaped protrusion).

[0076] The above coupling groove (222) may be configured to include a mounting groove (222a) that is open at the top and closed at the bottom and extends in a vertical direction, and a restraining groove (222b) that has an upward slope toward one side, i.e., in the circumferential direction, from the bottom of the mounting groove (222a), i.e., inclined at a predetermined angle upward in a direction away from the bottom of the mounting groove (222a) in the circumferential direction.

[0077] Preferably, in consideration of manufacturability and maintainability in the present invention, the projection (221) is formed on the manhole cover (120) and the coupling groove (222) is formed on the ring-shaped support member (110), and at least two of these projections (221) and coupling grooves (222) may be formed in a symmetrical relationship or multiple may be formed with spacing in the circumferential direction.

[0078] The operation in the case where a protrusion (221) is formed on the manhole cover (120) and a coupling groove (222) is formed on the ring-shaped support member (110) in the manhole cover locking-unlocking unit (200) configured as described above is explained as follows.

[0079] With the ring-shaped support member (110) and the manhole cover (120) combined, the projection (221) is positioned at 'A' in FIG. 4. In this case, the manhole cover (120) can be easily detached from the ring-shaped support member (110) for normal manhole work, etc.

[0080] And when water pressure acts upward due to backflow of rainwater from the manhole, this water pressure acts on the rotational force generating member (212) (twist blade) of the rotational force generating means (210), causing the manhole cover (120) to rotate, and at this time, the projection (221) moves upward from the position of the lower part of the mounting groove (222a) toward the restraining groove (222b) which is inclined at a predetermined angle. Accordingly, the manhole cover (120) is unable to detach from the ring-shaped support member (110) and remains in a restrained state.

[0081] Then, when the hydraulic pressure acting on the rotational force generating member (212) (twist blade) of the rotational force generating means (210) is released, the restraining groove (222b) is formed at an angle, so the protrusion (221) slides down the restraining groove (222b) due to the weight of the manhole cover (120) and is positioned back in the mounting groove (222a), so that the manhole cover (120) can be easily detached from the ring-shaped support member (110) for normal manhole work, etc., in the initial state.

[0082] The manhole cover locking-unlocking unit (200) of the above-described embodiment is configured to have a cam interlocking structure between a ring-shaped support member (110) and a manhole cover (120), so that normally the manhole cover (120) is in an openable state, and when water pressure is applied, the manhole cover (120) is rotated to one side at a predetermined angle so that the projection (221) goes up the restraining groove (222b), which is the cam surface, and locks, and when the water pressure is released, it goes down the cam surface so that it is in an openable state again.

[0083] Meanwhile, the manhole cover locking-unlocking unit (200) may further include a water pressure inducing means (230) that induces the water pressure acting on the rotational force generating member (212) (twist blade) of the rotational force generating means (210) to be biased to one side.

[0084] The above-mentioned hydraulic pressure inducing means (230) may be formed integrally at the lower part of the rotational force generating member (212) as shown in FIG. 4, and may be configured to have a flow path or an inclined surface so that the oil flow or working hydraulic pressure acting from the lower part is concentrated on one side.

[0085] Meanwhile, the loss-prevention type manhole cover device according to the first embodiment of the present invention may further include a constant fixation maintenance means (250) configured to be included in the manhole cover locking-unlocking unit (200) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0086] The above fixing holding means (250) may include a fixing holding groove (251) that extends a predetermined length in a horizontal direction from the upper end of the restraining groove (222b), a coupling groove or coupling hole (252) formed symmetrically on the upper edge of the manhole cover (120), and an operating jig (not shown) configured to be coupled to the jig coupling groove (252) to rotate the manhole cover (120).

[0087] The above coupling groove or coupling hole (252) may be formed symmetrically at 180° in the circumferential direction, formed at 90° intervals, or formed at 120° intervals.

[0088] Here, the coupling groove or coupling hole (252) can be kept closed with a plug or the like in normal circumstances.

[0089] The above operating jig may be composed of, for example, an inverted U-shaped or cross-shaped insertion part that is fitted or inserted into the coupling groove or coupling hole (252), and a handle part that is grasped and rotated by the user.

[0090] These fixed maintenance means (250) allow a worker to rotate the manhole cover (120) using an operating jig in cases where a flood or backflow is expected to occur by referring to weather information, etc., so that the protrusion (221) is positioned in the fixed maintenance groove (251), thereby keeping the manhole cover (120) fixed to the ring-shaped support member (110) at all times.

[0091] Additionally, the fixed holding means (250) may further include a movement restraining member (253) to prevent the projection (221) from moving to the other end while the projection (221) is positioned at one end (moving end) of the fixed holding groove (251).

[0092] The above-mentioned moving restraint member (253) is provided such that the upper part of the ring-shaped support member (111) in the drawing, where the coupling groove (222) is formed, is exposed to the outside and the lower part is threaded to the above-mentioned member, and is positioned on the ceiling surface on the side where the extension from the restraint groove (222b) begins, and on the side where the entrance of the fixed retaining groove (251) begins.

[0093] Accordingly, when the operator rotates the movable restraint member (253) to one side, the movable restraint member (253) protrudes from the upper surface of the fixed retaining groove (251) toward the inside of the fixed retaining groove (251), thereby preventing the projection (221) from moving toward the restraining groove (222b), and thus the state in which the projection (221) is positioned in the fixed retaining groove (251) can be maintained more stably.

[0094] Next, a loss-prevention type manhole cover device according to a second embodiment of the present invention will be described in detail with reference to FIGS. 7 and 8.

[0095] FIG. 7 is a schematic diagram showing a loss-prevention type manhole cover device according to a second embodiment of the present invention, and FIG. 8 is a diagram showing a manhole cover locking-unlocking unit included in the loss-prevention type manhole cover device according to a second embodiment of the present invention.

[0096] In the description of the loss-prevention type manhole cover device according to the second embodiment of the present invention below, the same reference numerals are assigned to components identical to those described in the loss-prevention type manhole cover device according to the first embodiment of the present invention, and detailed descriptions thereof are simplified or omitted for the sake of simplification and clarification of the description.

[0097] As shown in FIGS. 7 and 8, the loss-prevention type manhole cover device according to the second embodiment of the present invention comprises a ring-shaped support member (110), a manhole cover (120), and a manhole cover locking-unlocking unit (300), and may additionally include a constant fixing maintenance means (250).

[0098] Specifically, the loss-prevention type manhole cover device according to the second embodiment of the present invention comprises, as shown in FIGS. 7 and 8, a ring-shaped support member (110) provided at the opening of a manhole (a manhole entrance where a manhole cover is to be installed); a manhole cover (120) detachably provided at the central opening of the ring-shaped support member (110) to cover the opening of the manhole; and a manhole cover locking-unlocking unit (300) provided between the ring-shaped support member (110) and the manhole cover (120) configured so that the manhole cover (120) is automatically locked and unlocked to the ring-shaped support member (110) by means of a rainwater backflow state (water pressure action state) or a backflow release state (water pressure release state). In addition, the loss-prevention type manhole cover device according to the second embodiment of the present invention may further include a constant fixation maintenance means (350) configured to be included in the manhole cover locking-unlocking unit (300) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0099] The above ring-shaped support member (110) and manhole cover (120) are identical to those of the first embodiment described above, so a description thereof is omitted. Instead, the manhole cover locking-unlocking unit (300) and the constant fixing maintenance means (350), which are components different from those of the first embodiment, will be described.

[0100] In the second embodiment, the manhole cover locking-unlocking unit (300) includes an X-shaped link (310) whose two ends are rotatably coupled to the lower surface of the manhole cover (120), and a buoyancy member (320) coupled to the other end of the X-shaped link (310) and which rises due to water pressure or backflowing rainwater.

[0101] In the present invention, the length of the link constituting the X-shaped link (310) is formed to be larger than the inner diameter of the ring-shaped support member (110) or larger than the inner diameter of the manhole wall.

[0102] In the present invention, instead of the X-shaped link (310), the link members may be configured independently. That is, it may be composed of a first link, one end of which is rotatably coupled to one side of the edge of the lower surface of the manhole cover (120), and a second link, one end of which is rotatably coupled to the other side of the edge of the lower surface of the manhole cover (120) (preferably at a position 180° apart from the one end of the first link).

[0103] The above buoyancy member (320) may be formed as a tubular body made of plastic material and may be provided by being connected through a connecting link (321) as illustrated in the drawing.

[0104] In the second embodiment of the present invention configured as such, the buoyancy generating member (320) rises due to water pressure or backflowing rainwater, and accordingly, the link (310) linked to the buoyancy generating member (320) is restrained by being in close contact with the inner edge of the ring-shaped support member (110) or in close contact with the manhole wall.

[0105] At this time, as the water level of the backflowing rainwater rises, the buoyancy generating member (320) rises further, and in this case, the contact force of the other end of the link (310) becomes even greater, making the restrained state of the manhole cover (120) more secure so that it does not detach from the ring-shaped support member (110).

[0106] Meanwhile, the loss-prevention type manhole cover device according to the second embodiment of the present invention may also further include a constant fixation maintenance means (350) configured to be included in the manhole cover locking-unlocking unit (300) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0107] The above-mentioned constant fixed maintenance means (350) may be configured to include a fixed rod member (351) which is provided so that one end penetrates the manhole cover (120) and is exposed to the outside, and the other end is rotatably coupled to the other end of the link (X-shaped link) (310), and a catch (352) which is formed protruding from the inner edge of the ring-shaped mounting part (111) of the ring-shaped support member (110).

[0108] The upper part of the fixed rod member (351) is formed with an L-shaped head portion, and a ring (353) may be provided at the top of the head portion.

[0109] In addition, a seating groove (354) is formed on the manhole cover (120) on the side where the head portion of the fixed rod member (351) is provided, and a fixed seating groove (355) is formed on the other side in the rotational direction. Here, the bottom surface of the fixed seating groove (355) is formed higher than the height of the bottom surface of the seating groove (354). In other words, the height of the bottom surface of the fixed seating groove (355) is formed with a height that takes into account the distance at which the other end of the link (310) can be caught on the lower part of the catch (320) while the fixed rod member (351) is moved upward.

[0110] The constant fixed maintenance means (350) configured in this manner is maintained in a state where its head portion is seated in the seating groove due to the self-weight of the link (310) and the buoyancy member (320) during normal operation.

[0111] And in order to keep the manhole cover (120) in a fixed state, the operator uses a work jig to hook the fixing rod member (351) onto the loop (353) and lifts the fixing rod member (351) to a predetermined degree so that the other end of the link (310) is caught on the lower part of the catch (352), and then rotates the fixing rod member (351) so that it is seated in the fixing seat groove (355).

[0112] At this time, since the height of the bottom surface of the fixed mounting groove (355) is higher than the height of the bottom surface of the mounting groove (354), the other end of the link (310) connected to the fixed rod member (351) is in a state of being caught on the catch (320).

[0113] Next, a loss-prevention type manhole cover device according to the third embodiment of the present invention will be described in detail with reference to FIG. 9.

[0114] FIG. 9 is a drawing showing a loss-prevention type manhole cover device according to a third embodiment of the present invention.

[0115] A loss-prevention type manhole cover device according to the third embodiment of the present invention, as shown in FIG. 9, comprises a ring-shaped support member (110), a manhole cover (120), and a manhole cover locking-unlocking unit (400), and may additionally include a permanent fixing maintenance means (450).

[0116] Specifically, the loss-prevention type manhole cover device according to the third embodiment of the present invention comprises, as shown in FIG. 9, a ring-shaped support member (110) provided at the opening of a manhole (a manhole entrance where a manhole cover is to be installed); a manhole cover (120) detachably provided at the central opening of the ring-shaped support member (110) to cover the opening of the manhole; and a manhole cover locking-unlocking unit (400) provided between the ring-shaped support member (110) and the manhole cover (120) configured so that the manhole cover (120) is automatically locked and unlocked to the ring-shaped support member (110) by means of a rainwater backflow state (water pressure action state) or a backflow release state (water pressure release state). In addition, the loss-prevention type manhole cover device according to the third embodiment of the present invention may further include a constant fixation maintenance means (450) configured to be included in the manhole cover locking-unlocking unit (300) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0117] The ring-shaped support member (110) and the manhole cover (120) are identical to those in the first embodiment described above, so a description thereof is omitted, and the manhole cover locking-unlocking unit (400), which is a component different from the embodiment described above, is described.

[0118] In the third embodiment, the manhole cover locking-unlocking unit (400) comprises a plurality of guide rails (410) spaced radially on the lower surface of the manhole cover (120), a sliding member (420) movable back and forth along the guide rails (410), a moving force generating means (430) configured to drive the sliding member (420) back and forth in conjunction with backflowing rainwater or water pressure, and a locking groove (440) formed in the ring-shaped support member (110) so that the end of the sliding member (420) advancing by the moving force generating means (430) is inserted.

[0119] The guide rail (410) is configured so that the sliding member (420) can move back and forth without falling downward.

[0120] The above sliding member (520) can be formed in the form of a rod or a frame.

[0121] The above-mentioned means for generating movement force (430) includes a connecting link (431) having one end rotatably coupled to the other end of the sliding member (420), an up-and-down moving rod member (432) having the other end of the connecting link (431) rotatably coupled while inclined downward, and a buoyancy body or buoyancy member (433) provided at the lower end of the up-and-down moving rod member (432).

[0122] The other end of the above connecting link (431) is connected to the above vertical movement rod member (432) in a downwardly inclined state.

[0123] In the third embodiment of the loss-prevention type manhole cover device configured as described above, the buoyancy body (433) rises due to backflowing rainwater or water pressure, causing the vertical movement rod member (432) to rise, and the connecting link (431) linked to the vertical movement rod member (432) rotates with its other end as a rotation axis, and accordingly, the sliding member (520) connected to one end of the connecting link (431) moves forward, and the other end, which is the free end of the sliding member (520), is inserted into the locking groove (440) of the ring-shaped support member (110) to maintain the locking state of the manhole cover (120) while water pressure is applied.

[0124] And when the hydraulic pressure is released, the buoyancy body (433) moves downward by its own weight, and accordingly, the other end of the sliding member (520) moves out of the locking groove (440) of the ring-shaped support member (110), so that the manhole cover (120) can be separated from the ring-shaped mounting member (110).

[0125] Meanwhile, the third embodiment described above may also further include a constant fixing maintenance means (450) configured to be included in the manhole cover locking-unlocking unit (300) so that the manhole cover (120) is maintained in a constant fixed state (constant locking state or detachment prevention state) with respect to the ring-shaped support member (110).

[0126] The above-mentioned constant fixed maintenance means (450) may be configured such that one end penetrates the manhole cover (120) and is exposed to the outside, and the other end is a fixed rod member (451) coupled to the upper end of the vertically moving rod member (432).

[0127] The upper part of the fixed rod member (451) is formed to have an L-shaped head portion, and a ring (452) may be provided at the top of the head portion.

[0128] In addition, a seating groove (453) is formed on the side of the manhole cover (120) where the head portion of the fixed rod member (451) is provided, and a fixed seating groove (454) is formed on the other side in the rotational direction. Here, the bottom surface of the fixed seating groove (454) is formed higher than the height of the bottom surface of the seating groove (453). In other words, the height of the bottom surface of the fixed seating groove (454) is formed with a height that takes into account the travel distance at which the other end of the sliding member (520) can be inserted into the locking groove (440) and locked while the fixed rod member (451) is moved upward.

[0129] The constant fixed maintenance means (450) configured in this manner is maintained in a state where its head portion is seated in the seating groove (453) due to the self-weight of the buoyancy body (433) during normal times.

[0130] And in order to keep the manhole cover (120) in a fixed state, the operator uses a work jig to hook onto the loop (452) of the fixed rod member (451) and lifts the fixed rod member (451) to a predetermined degree so that the other end of the sliding member (520) is inserted into the locking groove (440), and then rotates the fixed rod member (451) at a predetermined angle so that it is seated in the fixed seating groove (454).

[0131] At this time, since the height of the bottom surface of the fixed mounting groove (454) is higher than the height of the bottom surface of the mounting groove (453), the other end of the sliding member (520) linked to the fixed rod member (451) is locked in the locking groove (440).

[0132] The above buoyancy body or buoyancy member (433) may be formed as a tubular body made of plastic material and may be provided by being joined through a connecting link as illustrated in the drawing.

[0133] Meanwhile, FIG. 20 is a drawing showing an automatic expansion means included in a loss-prevention type manhole cover device according to the present invention.

[0134] As shown in FIG. 20, the loss-prevention type manhole cover device according to the present invention may further include an automatic expansion means (510) configured to automatically expand when the manhole cover (120) is separated from the ring-shaped support member (110) by a certain distance or more, and a connecting cable (520) having one end connected to the ring-shaped support member (110) and the other end connected to the automatic expansion means (510).

[0135] The above automatic inflation means (510) may be configured as an automatic inflatable life vest. That is, the above automatic inflation means (510) may be composed of an inflation chamber formed of an inflatable material and detachably provided on the lower surface of the manhole cover (120) in a deflated state, a compressed air cylinder provided on one side of the inflation chamber, and an inflation trigger. The inflation trigger detaches along with the detachment of the manhole cover (120), thereby opening the compressed air cylinder to inject compressed air into the inflation chamber, and the inflated inflation chamber rises to the upper side where the manhole cover (120) was lost, thereby indicating that the manhole cover (120) has been lost at that point.

[0136] These automatic expansion means (510) can be applied to all of the above-described embodiments.

[0137] Meanwhile, FIG. 11 is a drawing showing a manhole closing auxiliary means included in a loss-prevention type manhole cover device according to the present invention.

[0138] The loss-prevention type manhole cover device according to the present invention may further include a manhole closing auxiliary means (600) for auxiliaryly closing the opening of the manhole when, despite the locking state described above, the locking-related components are damaged and the manhole cover (120) is dislodged from the ring-shaped mounting member (110).

[0139] The above manhole closing auxiliary means (600) includes an auxiliary manhole cover (610) having one end rotatably coupled to one side of a ring-shaped mounting member (110), a connecting member (620) having one end connected to the manhole cover (1200) and the other end coupled to the other end of the auxiliary manhole cover (610), and an auxiliary manhole cover fixing means (630) provided between the other end of the auxiliary manhole cover (610) and the ring-shaped mounting member (110) so that when the auxiliary manhole cover (610) rotates to close the manhole opening, the auxiliary manhole cover (610) is fixed to the ring-shaped mounting member (110).

[0140] The above auxiliary manhole cover (610) has a predetermined thickness and can be formed as a mesh-type or grill-type cover through which fluid can pass.

[0141] The above connecting member (620) may be composed of a chain or a wire.

[0142] The above auxiliary manhole cover fixing means (630) comprises an inclined portion (631) formed so that the upper surface of the other end of the auxiliary manhole cover (610) slopes downward, a sliding moving catch (632) configured on the ring-shaped mounting member (100) that retracts backward while in contact with the inclined portion (631) of the other end of the auxiliary manhole cover (610), and advances forward to be caught and supported on the lower surface of the other end of the auxiliary manhole cover (610) while the inclined portion (631) has passed over, and a stopper (633) formed on the upper part of the sliding moving catch (632) to restrict the rotation of the auxiliary manhole cover (610).

[0143] The distance between the sliding moving catch (632) and the stopper (633) is formed to be equal to or greater than the thickness of the auxiliary manhole cover (610).

[0144] The manhole closing auxiliary means (600) configured in this manner can prevent an accident caused by the loss of the (main) manhole cover (200) by having the auxiliary manhole cover (610), connected by the connecting member (620), rotate to close the manhole opening when the manhole cover (main manhole cover) (200) is dislodged from the manhole opening by water pressure or other external force.

[0145] According to the loss-prevention manhole cover device of the present invention as described above, the present invention can reliably prevent the manhole cover from being lost due to backflowing rainwater during rain, thereby preventing safety accidents caused by the loss of the manhole cover. Additionally, by automatically locking and unlocking the manhole cover in conjunction with the backflow state and the backflow release state (or normal state), normal manhole maintenance can be performed during normal times, and the loss of the manhole cover during backflow can be prevented, thereby preventing accidents such as loss of manhole cover, thus ensuring functionality and usability.

[0146] In addition, the present invention has the advantage of preventing safety accidents by enabling immediate notification of the manhole cover loss simultaneously with the loss of the manhole cover due to backflow of rainwater, thereby visually indicating the location of the loss, and allowing for easy identification of the loss point to respond quickly thereafter, and more effectively preventing safety accidents by covering the manhole opening with an auxiliary cover member and / or providing notification simultaneously with the loss of the manhole cover, and preventing incomplete fixation or loss of the manhole cover by preventing opening by external force or arbitrary opening by maintaining the manhole cover in a locked state and allowing it to be opened only by an operator's opening operation.

[0147] The embodiments described in this specification and the accompanying drawings are merely illustrative of a part of the technical concept included in the present invention. Accordingly, since the embodiments disclosed in this specification are intended to explain, not limit, the technical concept of the present invention, it is obvious that the scope of the technical concept of the present invention is not limited by these embodiments. All variations and specific embodiments that can be easily deduced by a person skilled in the art within the scope of the technical concept included in the specification and drawings of the present invention should be interpreted as being included within the scope of the rights of the present invention. Explanation of the symbols

[0149] 110: Ring-shaped support member 111: Ring-shaped mounting part 112: Ring-shaped wall 120: Manhole cover 200, 300, 400: Manhole cover locking-unlocking unit 210: Means for generating rotational force 211: Extension Load 212: Rotational force generating member 220: Automatic locking-unlocking means 221: Protrusion 222: Connecting groove 222a: Mounting groove 222b: Restraint Home 230: Hydraulic induction means 250, 350, 450: Means for permanent fixation 251: Fixed retaining groove 252: Jig joining groove (or joining hole) 253: No movement restraint 310: X-shaped link 320: Buoyancy member 351: Fixed rod member 352: Stopper 353, 452: Ring 354, 453: Settlement Home 355, 454: Fixed seating grooves 410: Guide rail 420: Sliding member 430: Means of generating mobility 431: Connection Link 432: Shanghai-dong Road Absence 433: Buoyancy element (buoyancy body) 440: Rocking Home 451: Fixed rod member 510: Automatic inflation means 520: Connection cable 600: Manhole closure auxiliary means 610: Auxiliary manhole cover 620: Connecting member 630: Auxiliary manhole cover fixing means 631: Slope 632: Sliding moving lock 633: Stopper

Claims

Claim 1 A ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover and configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure; wherein the ring-shaped support member is formed as a ring-shaped member with a cross-section 'T' or a cross-section 'L', and the manhole cover locking-unlocking unit includes a rotational force generating means coupled to the manhole cover at the bottom of the manhole cover and configured to generate rotational force by water pressure, and an automatic locking-unlocking means provided on the opposing surface between the ring-shaped support member and the manhole cover, configured to lock the manhole cover to the ring-shaped support member when water pressure is applied and to automatically release the locked state when the water pressure is released, and wherein the rotational force generating means is configured to include an extension rod extending downward from the center of the lower surface of the manhole cover and a rotational force generating member coupled to the extended end of the extension rod and generating rotational force by water pressure, or integrally formed on the lower surface of the manhole cover A loss-prevention type manhole cover device characterized by being formed and composed of a rotational force generating member that generates rotational force through hydraulic action. Claim 2 delete Claim 3 delete Claim 4 A loss-prevention type manhole cover device according to claim 1, wherein the rotational force generating member is formed in multiple numbers with spacing in the circumferential direction and is composed of twist blades formed by twisting so as to gradually increase or decrease from the center to the outer edge. Claim 5 A ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover and configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure; wherein the ring-shaped support member is formed as a ring-shaped member with a cross-section 'T' or a cross-section 'L', and the manhole cover locking-unlocking unit includes a rotational force generating means coupled to the manhole cover at the bottom of the manhole cover and configured to generate rotational force by water pressure, and an automatic locking-unlocking means provided on the opposing surface between the ring-shaped support member and the manhole cover, configured to lock the manhole cover to the ring-shaped support member when water pressure is applied and to automatically release the locking state when the water pressure is released, and wherein the automatic locking-unlocking means includes a projection formed on one of the inner edge of the ring-shaped support member and the outer edge of the manhole cover, and a projection formed on the other of the inner edge of the ring-shaped support member and the outer edge of the manhole cover, wherein A loss-prevention type manhole cover device comprising a coupling groove configured such that when a manhole cover is seated on a ring-shaped support member, the projection is mounted longitudinally and, when rotational force is generated by the rotational force generating means, the projection moves to one side to restrain the upward movement of the manhole cover, and when the hydraulic pressure is released, the projection moves to its original position; wherein the coupling groove comprises a vertical mounting groove portion in which the upper end is open upward and the lower end is closed, and a restraining groove portion formed at the lower end of the vertical mounting groove portion with an upward slope in the circumferential direction. Claim 6 A loss-prevention type manhole cover device according to claim 5, further comprising a constant fixing maintenance means configured to maintain the manhole cover in a constant fixed state with respect to the ring-shaped support member, wherein the constant fixing maintenance means comprises a fixing maintenance groove extending horizontally from the extended end of the restraining groove, a jig coupling groove formed symmetrically on the upper edge of the manhole cover, and an operating jig coupled to the jig coupling groove to rotate the manhole cover. Claim 7 delete Claim 8 A ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover and configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure; wherein the manhole cover locking-unlocking unit includes a link, one end of which is rotatably coupled to the lower surface of the manhole cover, and a buoyancy member coupled to the other end of the link, wherein the length of the link is formed to be larger than the inner diameter of the ring-shaped support member, and a constant fixing maintenance means configured to keep the manhole cover constantly fixed to the ring-shaped support member, wherein the constant fixing maintenance means includes a fixed rod member, one end of which is provided to penetrate the manhole cover and be exposed to the outside, and the other end of which is rotatably coupled to the other end of the link, and a locking projection formed protruding from the inner edge of the ring-shaped mounting part of the ring-shaped support member, wherein the fixed rod member is formed having an L-shaped head portion at its upper end, and a hook is provided at the upper end of the head portion, and wherein the head portion is provided on the manhole cover A loss-prevention type manhole cover device characterized by having a seating groove formed on one side and a fixed seating groove formed on the other side in a rotational direction, wherein the bottom surface of the fixed seating groove is formed higher than the height of the bottom surface of the seating groove. Claim 9 delete Claim 10 A ring-shaped support member; a manhole cover detachably provided on the ring-shaped support member; and a manhole cover locking-unlocking unit provided between the ring-shaped support member and the manhole cover and configured to lock and unlock the manhole cover to the ring-shaped support member in conjunction with water pressure; wherein the manhole cover locking-unlocking unit includes a plurality of guide rails provided at radially spaced intervals on the lower surface of the manhole cover, a sliding member provided to be movable back and forth along the guide rails, a movement force generating means configured to drive the sliding member back and forth in conjunction with water pressure, and a locking groove formed in the ring-shaped support member to insert the end of the sliding member advancing by the movement force generating means; wherein the movement force generating means includes a connecting link, one end of which is rotatably coupled to the other end of the sliding member, a vertical movement rod member, the other end of which is rotatably coupled while inclined downward, and a buoyancy member provided at the lower end of the vertical movement rod member, wherein the other end of the connecting link is provided coupled to the vertical movement rod member in a downward inclined state, and the manhole cover is on the ring-shaped support member A loss-prevention type manhole cover device comprising a constant fixation maintenance means configured to be constantly fixed, wherein the constant fixation maintenance means is configured such that one end penetrates the manhole cover and is exposed to the outside, and the other end is configured as a fixed rod member coupled to the upper end of the vertically moving rod member, wherein the fixed rod member is formed with an L-shaped head portion at the upper end and a hook is provided at the upper end of the head portion, wherein the manhole cover has a seating groove formed on one side for the head portion to be seated and a fixed seating groove formed on the other side in the rotational direction, and wherein the bottom surface of the fixed seating groove is formed higher than the height of the bottom surface of the seating groove. Claim 11 A loss-prevention type manhole cover device according to claim 1, further comprising: an automatic expansion means detachably coupled to the lower surface of the manhole cover and configured to automatically expand when the manhole cover is detached from a ring-shaped support member by a certain distance or more; and a connecting cable having one end coupled to the ring-shaped support member and the other end coupled to the automatic expansion means, wherein the automatic expansion means comprises an expansion chamber formed of an expandable material and detachably provided on the lower surface of the manhole cover in a contracted state, a compressed air cylinder provided on one side of the expansion chamber, and an expansion trigger that detaches together with the manhole cover when the manhole cover is detached, thereby opening the compressed air cylinder to inject compressed air into the expansion chamber.

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