JP2002327446A - Locking apparatus for manhole iron cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a locking apparatus for a manhole iron cover, which can positively prevent a locking portion thereof from being unlocked even if high pressure water is poured onto an iron cover body or the manhole iron cover is set on sloping ground. SOLUTION: The locking apparatus is comprised of a bracket 10 having an opening portion 11, the iron cover body 20 openably fitted into the opening 11, a hinge openably connecting the iron cover body 20 to the bracket 10, and a locking fixture 40 rockably pivoted onto a rear surface of the iron cover body 20, for disengageably engaging with an engaging projection 12 of the bracket 10. The locking fixture 40 is comprised of a pair of locking half bodies 41, a plug body 50 pivoted at a location between the locking half bodies 41 in a disengageable manner, for blocking a key hole 21 of the iron cover body 20, a bolt 58 and a nut 59 for connecting the locking half bodies 41 together, and a spring member 60 for engaging a hook portion 44 of each locking half body 41 in a direction that engages with the engaging projection 12 of the bracket 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a locking device for a manhole iron cover, and more particularly, to a manhole for closing an opening for communicating an underground buried object or an underground structure facility in a sewer with the ground. The present invention relates to a locking device for an iron lid.

[0002]

2. Description of the Related Art A conventional locking device for a manhole iron cover includes, for example, a receiving frame having a substantially circular opening communicating with an underground structure such as a sewer, opening and closing the opening of the receiving frame, and a locking position of the receiving frame. And an iron lid that is openably and closably fitted to the unlocked position, and a hinge that connects the iron lid to the receiving frame so as to be openable and closable, and further includes a hinge between the receiving frame and the iron lid. There is a structure in which a locking fitting is provided on the opposite side (see Japanese Patent No. 2935209).

In this type of locking device, when a stopper is used and the iron cover closes the opening of the receiving frame, the upper surface of the stopper substantially coincides with the upper surface of the iron cover. The height is adjusted so that the keyhole of the iron cover is closed and rainwater can be prevented from entering the receiving frame.

In the case where a stopper is used, it is possible that the stopper is pushed down by a tool such as a bur to rotate the locking half, and the hook portion of the locking half is released from the locking projection of the receiving frame and unlocked. I can do it. Since the pair of locking halves are connected by a connecting member, the pivots protruding on both sides of the iron lid are simply fitted into the recesses of the locking half so that the stopper can be easily rotated together with the locking half. I'm wearing

On the other hand, when the plug is removed from the iron cover and a pair of locking halves is used, the keyhole of the iron cover communicates with the inside and outside of the manhole, and the rainwater poured onto the road is used as a key. The hole can be introduced into the receiving frame.

When the plug is removed from the iron cover,
The locking half can be rotated by a tool such as a bur, and the hook portion of the locking half can be released from the locking projection of the receiving frame and unlocked.

[0007]

However, in the conventional locking device described above, when a stopper is used, when heavy rain or the like causes high-pressure water to act downward on the iron lid, the locking device uses the high-pressure water. While the stopper is pressed downward, the stopper may cause the hook portion of the locking half to turn in a direction to be disengaged from the locking projection of the receiving frame, and may be unlocked between the locking projection.

[0008] When the manhole iron cover is installed on an inclined ground, that is, when the manhole iron cover is installed on an inclined ground such that the pair of locking halves and the plug body are positioned higher than the hinge side, the locking half is closed. The hook portion of the body turns by its own weight in the direction of being disengaged from the locking projection of the receiving frame due to its own weight, and there is a risk that the locking half will be unlocked by its own rotation.
In particular, when the plug is installed on an inclined ground, when high-pressure water acts on the plug, the plug is pressed downward, and the hook portion of the locking half may easily come off from the locking projection of the receiving frame.

[0009] The present invention has been made in view of the above circumstances, and even if high pressure water is applied to the iron lid body, or even if the iron lid body is installed on a sloping ground, the locking portion is unlocked regardless of them. An object of the present invention is to provide a highly reliable locking device for a manhole iron lid, which can reliably prevent the locking of a manhole iron cover.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, a receiving frame having an opening, an iron cover that is openably and closably fitted into the opening of the receiving frame, and an iron cover are provided. A hinge for connecting one side of the body to the receiving frame so as to be openable and closable, and a pivotably pivotally connected to a back surface near a keyhole provided on the other side of the iron cover body; A locking fitting that is removably engaged with a locking projection provided on the peripheral surface,
The locking member is a pair of locking halves having a pivot pivotally attached to a bracket protruding from the back surface of the iron lid, a hook portion engageable with the locking projection, and a tool receiving portion. A plug body detachably pivotally mounted between the locking halves, and having a plug portion for closing the keyhole, and an engaging portion which engages with the locking half when the plug portion is pressed down by a tool. And a connecting member for connecting the two locking halves, and a spring member for urging the elastic force in a direction in which the hook portion is engaged with the locking projection.

[0011] In the present invention, the locking member includes the pair of turning halves, the plug, and the connecting member as described above, and further, the hook portions of the pair of turning halves are engaged with the locking projections of the receiving frame. A spring member is also provided to urge the elastic force in the direction of joining, so that when the iron lid is in a state in which the opening of the receiving frame is closed, a heavy rain or the like causes a height from the keyhole of the iron lid to the plug. Even if a pressure is applied, the iron cover can always be forcibly locked to the receiving frame by the elastic force of the spring member.

Further, even if the manhole iron cover is installed on an inclined ground, that is, the manhole iron cover is installed so that the lock fitting side is located at a position higher than the position of the hinge, as described above, the elastic force of the spring member is maintained. Thus, since the iron lid is forcibly locked to the opening of the receiving frame, it is possible to reliably prevent the iron lid from opening from the receiving frame.

Therefore, even if high-pressure water acts on the plug body as in the prior art, or is installed in an inclined state, it is possible to reliably prevent the hook portion from coming off from the locking projection without being concerned with them. Reliability as a locking function can be improved.

In the prior art, the pair of turning halves have a function as a weight of the iron lid, so that not only the turning halves but also the plugs are formed to be heavy. As described above, since the locking is performed by utilizing the elastic force of the spring member, the entire locking fitting can be reduced in weight.

In the present invention, the structure of the spring member is arbitrary as long as the spring member urges the elastic force in a direction in which the hook portion of the locking half is engaged with the locking projection of the receiving frame. Preferably, the spring member extends from one end of the coil part interposed between the pivot of the locking half and the mounting hole provided in the bracket of the iron lid. And a second locking portion extending from the other end of the coil portion and engaging with a side of the locking half opposite to the hook portion. It is better to have.

With this configuration, since the coil portion is interposed between the pivot of the locking half and the mounting hole provided in the bracket of the iron lid, the space for disposing the spring member is reduced. And the locking fitting can be made compact.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a locking device for a manhole iron cover according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing a locked state of a manhole iron cover provided with a locking device according to a first embodiment of the present invention. FIG. FIG. 3 is a sectional view of a main part showing the unlocked state of the iron cover of the manhole, FIG. 4 is a bottom view showing a part of an attached state of the locking device of the present invention in cross section, and FIG. 5 is a perspective view of the locking device. FIG. 6 and FIG. 6 are exploded perspective views of the locking device.

As shown in FIGS. 1 and 2, the locking device has a receiving frame 10 having a substantially circular opening 11 communicating with an underground structure, and the opening and closing of the opening 11 of the receiving frame 10 as well as the receiving frame 10. And an iron cover 20 which is openably and closably fitted to the locked position and the unlocked position.

The iron lid 20 and the receiving frame 10 are formed so that the iron lid 20 can be opened and closed via a hinge 30 detachably connected to a hinge receiving seat 33 provided on the receiving frame 10. Further, a keyhole 21 is provided at a peripheral edge of the iron cover 20 opposite to the hinge 30 so that a tool K such as a bur can be inserted (see FIG. 3).

In this case, the opening 11 of the receiving frame 10 has a taper whose diameter increases toward the upper end, and the iron cover 20
Has a tapered surface whose diameter is reduced toward the back surface side, and the outer periphery of the iron cover 20 and the inner peripheral surface of the receiving frame 10 are fitted by the tapered surface to prevent rattling. I have. In addition,
The tool K is used when an operator opens and closes the iron cover 20 from the receiving frame 10.

A receiving frame 1 is provided on the back edge of the iron cover 20.
The lock fitting 40 is provided so as to be removably engaged with the locking projection 12 provided on the inner peripheral surface of the lock. In this case, the lock fitting 40 includes a pair of lock halves 41 and the keyhole 2 of the iron lid 20.
1 and a connecting member (not shown) for connecting the pair of locking halves 41 to each other.

As shown in FIGS. 4 to 6, the pair of locking halves 41 function as weights of the iron cover 20, and each has a symmetrical shape. Mounting hole 2 of bracket 22 protruding from back surface of lid 20
Pivot shafts 42 and 43 are provided, which are pivotally connected to 3, 24. In addition, a hook portion 44 formed in a hook shape that can be engaged with the locking projection 12 of the receiving frame 10 is provided below the locking half 41. As shown in FIGS. 1 to 3, the locking projection 12 is provided at a position corresponding to the locking half 41 on the inner peripheral surface of the receiving frame 10 so as to project toward the locking half 41. Further, inside the locking half 41, a receiving portion 45 of a tool that forms a linear plane is formed. This receiving part 4
Numeral 5 is used when a plug 50 to be described later is not used, and has a flat upper end. In addition, either one of the abutting surfaces of the locking halves 41 facing each other is
As shown in FIG. 2, a projection 41a for positioning is protruded, and a concave portion (not shown) for fitting with the projection 41a is provided on the other contact surface. It is not always necessary to provide the positioning projection 41a and the recess.

On the other hand, the plug 50 is used in accordance with the purpose of use of the manhole iron cover, and includes a pair of locking halves 4.
It is detachably connected between the two. In this case, the plug 50
The keyhole 21 is closed by closing the keyhole 21 of the iron cover 20.
It is for suppressing infiltration of rainwater and the like from the outside, and a plug portion 51 in the form of a flat plate which is large enough to close the keyhole 21 is formed at one end, and lateral plugs are formed at both sides of the other end. 6 are formed, and the shafts 52 are, as shown in FIG.
6 so that the locking halves 41 can be pivotally connected to each other.

When the plug 51 is pushed down by the tool K as shown in FIG. 3, the plug 50 rotates counterclockwise about the shaft 52. At this time, as shown in FIG. And an engaging portion 53 formed by bulging a part of the shaft 52.
The bottom surface 54 of the lock half 41 engages the notch 47 of the lock half 41 to rotate the lock half 41 counterclockwise, and the hook 44 of the lock half 41 engages with the locking projection 12 of the receiving frame 10. It is to be released from the case.

As shown in FIGS. 4 to 6, the connecting member comprises a bolt 58 and a nut 59. The bolt 58 is inserted into an insertion hole 48 penetrating through each locking half 41.
The two locking halves 41 are connected to each other in a state where they are in close contact with each other by tightening a nut 59 to a distal end portion of the bolt 58 while passing the distal end of the locking half. In this case, one end side of the insertion hole 48 has a hexagonal concave portion 48a.
Are arranged continuously, and a nut 59 is accommodated in the recess 48a (see FIG. 5).

The locking member 40 further includes a spring member 60 for urging the hook portion 44 of the locking half 41 in the direction of engaging with the locking projection 12 of the receiving frame 10. As shown in FIG. 6, the spring member 60 includes a coil portion 61, a first locking portion 62 extending from one end of the coil portion 61, and a second locking portion 62 extending from the other end of the coil portion 61. And a locking portion 63.

This spring member 60 is, as shown in FIG.
A coil portion 61 is interposed between the pivot 42 of the locking half 41 and the mounting hole 23 provided in the bracket 22, and as shown in FIGS. 2 and 3, the first locking portion 62 is an iron lid. 2
0, and the second locking portion 63 engages with a hooking portion 49 provided on the side opposite to the hook portion 44 of the locking half 61, so that the locking half can be elastically moved. 4
The first hook portion 44 is urged in a direction for engaging with the locking projection 12. Therefore, the spring member 60 is interposed between the pivot 42 of the locking half 41 and the mounting hole 23 in a state where the torsional force is sufficiently stored in advance. In this case, the pivot 42
Due to the interposition of the spring member 60, the mounting hole 2 is formed to be larger than the other pivot 43 and is fitted to the pivot 42.
3 is also formed in a size corresponding to it.

In order to mount the spring member 60, the coil portion 61 is positioned in the mounting hole 23 by passing the first locking portion 62 from the inside of the bracket 22 through the mounting hole 23, and then the bracket With the first locking portion 62 protruding outward from the metal cover 22 pressed against the back surface of the iron lid 20, the pivot 42 of one locking half 41 is inserted into the coil portion 61,
The coil part 61 is interposed between the pivot 42 and the mounting hole 23. At this time, the second locking portion 63 is engaged with a hook portion 49 provided on the side opposite to the hook portion 44 of the locking half 41.

The pivot 42 of the locking half 41 is connected to the mounting hole 2.
3 before inserting the plug 50 between the locking halves 41.
Is pivotally connected, that is, the shaft 52 of the plug 50 is fitted into the concave portion 46 provided in the locking half 41. In this state, the pivot 43 of the other locking half 41 is inserted into the mounting hole 24, and the pivot 42 of the locking half 41 is inserted into the mounting hole 23. At this time, the mounting hole 24 is
2, the pivot 43 is formed in a tapered shape in which the diameter decreases toward the tip, so that the locking half 41 can be easily attached to the bracket 22. Can be

Both locking halves 41 thus mounted
Are connected by bolts 58 and nuts 59.

As shown in FIG. 1, the hinge 30 is pivotally attached to a bracket provided on the periphery of the back surface of the iron cover 20 opposite to the locking fitting 40, and protrudes downward. It has a hinge body 31 and a locking wing piece 32 projecting slightly below the intermediate portion of the hinge body 31. The hinge seat 33 that detachably engages the hinge 30 configured as described above includes a pair of side pieces 34 that project downward and inward from the inner peripheral surface of the receiving frame 10 and a pair of side pieces 34. A receiving seat body 36 having a substantially U-shape in plan view, comprising a connecting piece 35 for connecting the distal end portion, and an inner peripheral surface side of the receiving frame 10 opposed to the connecting piece 35 of the receiving seat body 36, A locking piece 37 with which the stop blade piece 32 can be engaged;
A socket (not shown) for the hinge 30 is formed.

As shown in FIG. 1, the iron cover 20 constructed as described above is connected to a receiving frame 10 by a hinge 30 so that the iron cover 20 can be opened and closed. , As shown in FIGS. 1 and 2,
The hook portion 44 of the locking half 41 is connected to the locking projection 12 of the receiving frame 10.
And the plug part 51 of the plug body 50 is
It is assumed that the keyhole 21 is closed.

At this time, the tip K1 of the tool K such as a bur
3 is inserted into the keyhole 21 of the iron cover 20, and its tip K1 is hooked on a tool hooking portion 26 provided on the back surface of the iron cover 20. When the plug 51 of the plug 50 is pushed down by the heel K2 of the K, the plug 50 pivots counterclockwise in FIG. 3 and the bottom of the engaging portion 53 of the shaft 52 with the rotation of the plug 50. 54 engages with the notch 47, and the locking half 41 rotates counterclockwise together with the plug 50 so that the hook 44 of the turning half 41 is disengaged from the locking projection 12 of the receiving frame 10 and engaged. Is released.

When the tool K is lifted when the hook 44 of the locking member 40 is disengaged from the locking projection 12 of the receiving frame 10 as described above, the hinge 30 moves to the opening 11 of the receiving frame 10. One end of the iron cover 20 can be opened with the center as the center.

On the other hand, as described above, the iron cover 20 is
When the iron cover 20 is open from zero, the iron lid 20 is returned to the original position of the receiving frame 10 by performing the above-described procedure in the reverse order. That is, the tool K is lowered and the iron cover 20 is placed in the opening 1 of the receiving frame 10.
1 and the tip of the tool K is hooked on the tool 2
6 and taken out of the keyhole 21, the locking fitting 40
The elastic force of the spring member 60 interposed on the pivot 42 of the locking half 41 acts on the hook half 44 of the locking half 41 by rotating the locking half 41 clockwise in FIG. Is engaged with the locking projection 12 of the receiving frame 10 and the stopper 50 is rotated clockwise by the locking half 41.
Is also rotated clockwise so that the plug 51 of the plug 50 is
The plug portion 51 rises to the position of the keyhole 21 of the keyhole 21.
Will be closed. Thereby, since the keyhole 21 is closed by the plug 50, it is possible to suppress rainwater or the like from penetrating downward from the upper surface of the iron lid 20.

In the lock fitting 40 of this embodiment,
As described above, in addition to including the pair of turning halves 41, the plug 50, and the connecting member including the bolts 58 and the nuts 59, the hook portions 44 of the pair of turning halves 41 are engaged with the locking projections of the receiving frame 10. 12 is also provided with a spring member 60 that urges the elastic force in the direction in which the iron cover 20 is engaged with the iron cover 20 when the opening 11 of the receiving frame 10 is closed. Even if high pressure acts on the plug 50 from the keyhole 21 of the iron cover 20, the iron cover 20 is always held by the elastic force of the spring member 60.
Can be forcibly locked.

As described above, even if the manhole iron cover is installed on an inclined ground, that is, the manhole iron cover is installed so that the lock fitting 40 is located at a position higher than the position of the hinge 30, the spring member 60 is not moved. Since the iron cover 20 is forcibly locked to the opening 11 of the receiving frame 10 by the elastic force of the above, the opening of the iron cover 20 from the receiving frame 10 can be reliably prevented.

Therefore, even if high-pressure water acts on the plug body as in the prior art, or even if it is installed in an inclined state, the hook portion 44 can be engaged with the locking projection 1 regardless of them.
2 can be reliably prevented, and the reliability as a locking function can be enhanced.

Further, in the prior art, a pair of locking halves 41
In order to make the iron lid 20 function as a weight of the iron cover 20, not only the locking half 41 but also the stopper 50 is formed to be heavy, but as described above, the elastic force of the spring member 60 is used. Since the lock fitting 40 is configured so as to be locked, the entire lock fitting 40 can be reduced in weight.

Further, the spring member 60 includes a coil portion 61, a first locking portion 62 extending at one end thereof, and a second locking portion 63 extending at the other end thereof. Since the portion 61 is interposed between the pivot 42 of the locking half 41 and the mounting hole 23 provided in the bracket 22 of the iron cover 20, the space for disposing the spring member 60 can be reduced, and The locking fitting 40 can be made compact.

In the illustrated embodiment, the spring member 60 is provided with one of the locking halves 41 of the pair of locking halves 41.
Although an example is shown between the pivot 42 and the mounting hole 23 of the locking half 41, it is of course possible to provide it between the pivot 43 and the mounting hole 24 of the other locking half 41.

In the above embodiment, the locking fitting 40
As an example, the example using the plug 50 is shown.
The case where is not used is described.

7 to 9 show a second embodiment. That is, the locking fitting 40 of the second embodiment includes a pair of locking halves 41, a bolt 58 and a nut 59 as connecting members for connecting the pair of locking halves 41 to each other.
And a spring member 60. As shown in FIG. 7, the iron cover 20 is closed in the opening 11 of the receiving frame 10 via the hinge 30, and the hooks 44 of the pair of locking halves 41 are locked by the locking fitting 40. When it is engaged with the projection 12, the keyhole 2 of the iron lid 20 is
When 1 is opened, rainwater on the iron cover 20 is positively dropped from the keyhole 21 and is used for rainwater pipes. Note that the pair of locking halves 41
The bolts 58 and nuts 59 as connection members, and the spring member 60 are configured as shown in FIGS. 9 and 10 and are completely the same as in the above-described first embodiment. Omitted.

In order to unlock the lock fitting 40 from the state shown in FIG. 7, the tip K1 of a tool K such as a crowbar is inserted through the keyhole 21 of the iron cover 20, and the heel K2 is locked by a pair of locks. While being pressed against the receiving portion 45 of the half body 41, the tip portion K1 of the tool K is hooked on the tool hooking portion 26 provided on the back surface of the iron lid 20, and thereafter, the receiving portion 45 is pressed by the heel portion K2.
When the lock half 41 is depressed, the pair of locking halves 41 rotate counterclockwise, and
When the iron cover 20 is lifted in this state, the iron cover 20 is opened around the hinge 30.

In order to close the iron cover 20, the procedure reverse to that described above is performed. When the tip K 1 of the tool K is pulled out from the keyhole 21, the hook of the locking half 41 is pulled by the elastic force of the spring member 60. Locking can be performed by the tip of the portion 44 rotating clockwise and engaging with the locking projection 12 of the receiving frame 10.

According to the second embodiment, by pressing down the receiving portions 45 of the pair of locking halves 41 using the tool K, the locking halves 41 are disengaged against the elastic force of the spring member 60. Can be rotated. Therefore, the iron cover 20 can be locked to the receiving frame 10 by the elastic force of the spring member 60 regardless of whether the plug 50 is used or not depending on the use purpose of the manhole iron cover. Can obtain the same effect as in the embodiment.

[0048]

As described above, since the present invention is configured as described above, the following excellent effects can be obtained.

(1) According to the first aspect of the present invention, there is provided a receiving frame, an iron cover, a hinge, and a locking member, and the locking member relates a hook portion of a pair of locking halves to a locking projection. Because it is configured to have a spring member that urges the elastic force in the direction of joining, even if high-pressure water acts on the plug, or even if it is installed in an inclined state, the hook part is not affected by them. The locking projection can be reliably prevented from coming off from the locking projection, which has the effect of increasing the reliability of the locking function. Further, since the locking can be performed by using the elastic force of the spring member, the locking is achieved. There is also an effect that the entire device can be reduced in weight.

(2) According to the second aspect of the present invention, the spring member is provided between the pivot shaft of the locking half and the mounting hole provided in the bracket of the iron lid, and the coil member. A first locking portion extending from one end of the locking portion and pressed against the back surface of the iron cover, and a second locking portion extending from the other end of the coil portion and engaging with a side opposite to the hook portion of the locking half. Since the locking portion is provided, in addition to the above (1), the arrangement space for the spring member can be further reduced, and the locking fitting can be made compact.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a locked state of a manhole iron cover provided with a locking device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a locked state of the iron cover of the manhole.

FIG. 3 is a sectional view of a main part showing an unlocked state of the iron cover of the manhole.

FIG. 4 is a bottom view showing a part of the mounting state of the locking device of the present invention in a cross section.

FIG. 5 is a perspective view of a lock according to the present invention.

FIG. 6 is an exploded perspective view of the lock.

FIG. 7 is a sectional view of a main part showing a locked state of a manhole iron cover provided with a locking device according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a main part showing the unlocked state of the iron cover of the manhole.

FIG. 9 is a perspective view of a lock according to a second embodiment.

FIG. 10 is an exploded perspective view of a lock according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Receiving frame 11 Opening part 12 Locking projection 20 Iron cover 21 Key hole 22 Bracket 23, 24 Mounting hole 30 Hinge 40 Locking bracket 41 A pair of locking halves 42, 43 Axis 44 Hook part 45 Tool receiving part 46 Recess 47 Notch Part 48 insertion hole 50 plug body 51 plug part 52 shaft 53 engaging part 58 bolt (connecting member) 59 nut (connecting member) 60 spring member 61 coil part 62 first locking part 63 second locking part K tool

Claims (2)

[Claims] 1. A receiving frame having an opening, an iron cover that is openably and closably fitted to the opening of the receiving frame, and a hinge that connects one side of the iron lid to the receiving frame so as to be openable and closable. And pivotally pivotally attached to a back surface near a keyhole provided on the other side of the iron cover, and releasably engages with a locking projection provided on an inner peripheral surface of the receiving frame. A locking shaft, which is pivotally attached to a bracket projecting from the back surface of the iron cover, a hook portion engageable with the locking projection, and a tool receiving portion. A pair of locking halves having: a locking portion that is detachably pivotally mounted between the locking halves, closes a keyhole, and engages with the locking halves when the plug portion is pressed down by a tool. A plug having an engaging portion, a connecting member for connecting the two locking halves, and a hook for engaging the hook portion with the locking protrusion. Locking device manhole iron lid, characterized by comprising a spring member for urging the sexual power. 2. The locking device for a manhole iron cover according to claim 1, wherein the spring member includes a coil portion interposed between a pivot of the locking half and a mounting hole provided in a bracket of the iron cover. A first locking portion extending from one end of the coil portion and pressed against the back surface of the iron lid, and engaging with a side of the locking half opposite to the hook portion extending from the other end of the coil portion. A locking device for a manhole iron lid, comprising: