JP7649726B2 - Closure of manhole cover opening tool engagement hole - Google Patents

Description

The present invention relates to a closing device that is attached to a manhole cover to close an engagement hole for hanging an operating tool for opening and closing the manhole cover when not in use.

When opening a manhole cover for inspection and repair of underground pipes, etc., the T-shaped tip of a rod-shaped hand key, which is an opening and closing tool, is inserted into a keyhole (engagement hole) provided in the manhole cover, and the T-shaped tip is engaged with the lower surface of the hole edge of the engagement hole to lift and open the manhole cover. As a means for preventing unauthorized opening of the manhole cover, a blind plug is attached to the engagement hole of the manhole cover to close it when it is not in use (for example, Patent Document 1).
In the blind plug device described in Patent Document 1, a main shaft is rotatably supported by a main body that fits into an engagement hole, and a tightening nut is screwed onto the threaded rod of the main shaft. The tightening nut engages with a vertical slot in the main body, and rises along the slot as the main shaft rotates in the forward direction. When the tightening nut comes into contact with the underside of the manhole cover, it clamps the hole edge between the main body and the disk part at the top of the main body. This causes the main body to close the engagement hole and be fixed so that it cannot be removed.

Japanese Patent Application Publication No. 10-205184

In the above conventional blind plug device, the threaded rod of the shaft and the vertical slot of the main body are made quite long to accommodate several types of manhole covers with different thicknesses of the hole edge, so that when installing the device, the main shaft must be rotated many times in the forward direction until the tightening nut comes into contact with the bottom surface of the hole edge from a predetermined position at the bottom of the slot, and when removing the device, the main shaft must be rotated many times in the reverse direction until the tightening nut reaches a predetermined position at the bottom of the slot of the main body, which is a cumbersome task.
Therefore, an object of the present invention is to provide a closure device that can be universally applied to several types of manhole covers having different thicknesses of the hole edge portion and that can be easily attached and removed.

In the following description, reference will be made to the numerals in the accompanying drawings, but the invention is not limited thereto.
In order to solve the above problems, the obturator 1 of the present invention is a obturator 1 that is attached to a manhole cover 101 to block the engagement hole 102 for inserting an opening tool, the engagement hole 102 being made up of a circular hole 102a and an elongated hole 102b extending on both sides of the circular hole 102a. The obturator 1 includes a main body 2 that includes an umbrella portion 4 placed on the upper surface of the manhole cover 101 to block the engagement hole 102, a cylindrical cylinder portion 5 that extends downward from the lower surface of the umbrella portion 4 so as to penetrate the engagement hole 102, and a lock mechanism 3 that includes a rotor 7, a weak pressure spring 8, a locking member 9, and a strong pressure spring 10 that are successively assembled from above into the cylinder portion 5. The umbrella portion 4 includes an engagement protrusion 6 that engages with the elongated hole portion 102b of the engagement hole 102 to regulate the mounting position of the cylinder portion 5 around the axis relative to the engagement hole 102. The cylinder portion 5 has an upper end that is open on the umbrella portion 4 through a circular opening 11, a lower end that is closed by a bottom cover 12, and a guide projection 13 on the inner periphery and a guide opening 14 on the side wall. The guide projection 13 engages with the outer periphery of the rotor 7 to guide its rotation around the axis and its vertical movement. The guide opening 14 guides the rotation around the axis and the vertical movement of the locking member 9. The rotor 7 has a tool hanging portion 15 at its upper end that is exposed from the circular opening 11 so that an operating tool can be hung, and a cylindrical portion 16 that continues below the tool hanging portion 15. The rotor 7 can rotate around its axis between three positions: an unlocked position, a locked position 90° away from the unlocked position, and a fixed position that is at an angle less than 90° away from the unlocked position. The rotor 7 can also move up and down between an upper closed position where the tool hanging portion 15 closes the circular opening 11, and a lower pressed-down position where the tool hanging portion 15 is pushed into the cylinder portion 5. The rotor 7 is biased to the closed position by a weak pressure spring 8 and fitted into the cylinder portion 5. The cylindrical portion 16 of the rotor 7 is provided on its outer periphery with a guide groove 17 that engages with the guide projection 13, and has an engagement portion 18 on its underside, which is made up of an annular row of teeth that have a sawtooth cross section. The engagement portion 18 engages with the locking member 9 in the rotational direction when the rotor 7 is in the pressed-down position, and can rotate the locking member 9. The locking member 9 is provided with a crowned portion 19 and a locking piece 20. The crowned portion 19 has a corresponding engagement portion 21 on its upper surface, which is made up of an annular row of teeth that have a sawtooth cross section that can be engaged with and disengaged from the engagement portion 18 of the rotor 7. The locking piece 20 extends radially outward from a radially opposing portion of the crowned portion 19, and movably passes through the guide opening 14 of the cylinder portion 5. The locking member 9 is rotated and driven up and down by the rotor 7 via the engagement portions 18, 21, and can rotate 90° between an unlocked position in which the locking piece 20 faces the long hole portion 102b of the engagement hole 102, and a locked position in which the locking piece 20 is perpendicular to the long hole portion 102b.The locking member 9 can also move up and down between a lower separated position and an upper abutment position, and is biased by the strong pressure spring 10 to the upper abutment position and fitted into the cylinder portion 5. The guide groove 17 of the rotor 7 engages with the guide protrusion 13 of the cylinder portion 5 so as to be freely movable relative to the cylinder portion 5, and thereby guides the rotation and up and down movement of the rotor 7 relative to the cylinder portion 5. The guide groove 17 includes a first rotation guide groove 17c extending at the upper end of the cylindrical portion 16 from the first end 17a to the second end 17b over a rotation angle of 90° in the horizontal direction, an up-down guide groove 17d extending vertically downward from the second end of the first rotation guide groove 17c, and a second rotation guide groove 17f continuing from the lower end of the first rotation guide groove 17c and extending horizontally to the rotation end 17e over a rotation angle of less than 90° in the opposite direction to the first rotation guide groove 17c. The guide opening 14 of the cylinder portion 5, through which the lock piece 20 passes, guides the rotation and vertical movement of the locking member 9 relative to the cylinder portion 5, and includes a rotation guide opening 14c extending from a first end 14a to a second end 14b over a rotation angle of 90° in the horizontal direction, and a vertical guide opening 14e continuing from the second end 14b and extending vertically upward to the lock end 14d. The relationship between the operations of the cylinder portion 5, the rotor 7, and the locking member 9, and the relative positions of the guide projection 13, the guide groove 17, and the guide opening 14, and the lock piece 20 is set as follows. When the rotor 7 is in the pressed-down position and in the unlocked position with the locking member 9 and the engagement portions 18, 21 engaged, the guide protrusion 13 of the cylinder portion 5 is at the first end 17a of the first rotation guide groove 17c of the rotor 7, the locking piece 20 of the locking member 9 is at the first end 14a of the rotation guide opening 14 of the cylinder portion 5, and is in the unlocked position where it can pass vertically through the long hole portion 102b of the engagement hole 102. When the rotor 7 rotates together with the locking member 9 in the pressed-down position from the unlocked position to the locked position, the guide protrusion 13 moves relatively from the first end 17a to the second end 17b of the first rotation guide groove 17c of the rotor 7, and at the same time, the rotor 7 rises together with the locking member 9 due to the biasing force of the springs 8, 10, and the guide protrusion 13 moves relatively to the lower end of the vertical guide groove 17d. During this movement, the lock piece 20 of the lock member 9 moves from the first end 14a to the second end 14b of the rotation guide opening 14 of the cylinder portion 5, and at the same time, it rises to the lock end 14d of the upper and lower guide openings 14e by the biasing force of the springs 8, 10 and moves to the locked position. At the locked position, the lock piece 20 clamps the outer edge of the circular hole portion 102a of the engagement hole 102 between itself and the underside of the umbrella portion 4, making it impossible to remove the obturator 1 from the engagement hole 102. When the rotor 7 rotates further from the locked position to the fixed position, the lock piece 20 of the locking member 9 is at the lock end 14d of the rotation guide opening 14 of the cylinder portion 5, preventing the locking member 9 from rotating and stopping it at the locked position, while the guide projection 13 of the cylinder portion 5 moves relatively from the lower end of the upper and lower guide grooves 17d of the rotor 7 to the rotation end 17e of the second rotation guide groove 17f, and the rotor 7 rotates independently to the fixed position while causing the engagement portions 18, 21 to rotate freely due to the elasticity of the spring 8. When the rotor 7 is in the fixed position, the locking member 9 maintains the locked position, and the guide projection 13 of the cylinder portion 5 is at the rotation end 17e of the second rotation guide groove 17f of the rotor 7, preventing the rotor 7 from being pushed down.

According to the present invention, by pushing and rotating the rotor 7 from the unlocked position to the locked position, the locking member 9 is instantly placed in the locked position, and by releasing the rotor 7, the springs 8 and 10 push up the locking member 9, automatically bringing it into contact with the underside of the edge of the engagement hole 102 at a predetermined position corresponding to the thickness of the manhole cover 101, so that the engagement hole 102 can be easily blocked. Furthermore, by rotating the rotor 7 to the fixed position, the rotor 7 is fixed in the vertical direction, so that no obstacles to walking are created.

FIG. 2 is an exploded perspective view showing a closure device and a manhole cover according to an embodiment of the present invention. 2 is a plan view showing the relationship between the closure of FIG. 1 and an engagement hole in an unlocked state. FIG. 2A-A cross-sectional view FIG. 2 is a right side view of the closure of FIG. 1 in an unlocked state. 2 is a plan view showing the relationship between the closure device of FIG. 1 and an engagement hole in a locked state. FIG. 5A-B cross-sectional view of FIG. FIG. 2 is a right side view of the closure of FIG. 1 in a locked state. 2 is a plan view showing the relationship between the closure device of FIG. 1 and an engagement hole in a fixed state. FIG. 8C-C sectional view of FIG. FIG. 2 is a right side view of the occluder of FIG. 1 in a fixed state. FIG. 2 is a plan view of the body of the obturator of FIG. 1; FIG. 2 is a front view of the body of the obturator of FIG. 1; FIG. 2 is a side view of the body of the obturator of FIG. 1; This is a cross-sectional view taken along the line D-D of FIG. This is a cross-sectional view taken along line E-E of FIG. FIG. 2 is a plan view of the rotor of the occluder of FIG. 1; FIG. 17 is a front view of the rotor of FIG. 16 . FIG. 17 is a right side view of the rotor of FIG. 16 . 16A-16C cross-sectional view 16A-16C cross-sectional view 16 along the line HH in FIG. FIG. 2 is a plan view of a locking member in the occluder of FIG. 1; FIG. 2 is a front view of a locking member in the occluder of FIG. 1; This is a cross-sectional view taken along line II of Figure 22. 2A shows the positional relationship of each component in the unlocked state of the closure device in Figure 1, where (a) is a plan view, (b) shows the positional relationship between the guide groove and the guide protrusion, and (c) is an explanatory diagram showing the positional relationship between the guide opening and the lock piece. 2A shows the positional relationship of each component when the closure device in Figure 1 is in the locked state, where (a) is a plan view, (b) shows the positional relationship between the guide groove and the guide protrusion, and (c) is an explanatory diagram showing the positional relationship between the guide opening and the lock piece. 2A shows the positional relationship of each component when the obturator of Figure 1 is in a fixed state, where (a) is a plan view, (b) shows the positional relationship between the guide groove and the guide protrusion, and (c) is an explanatory diagram showing the positional relationship between the guide opening and the lock piece.

The embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the engagement hole 102 of the manhole cover 101 to which the obturator 1 is attached consists of a central circular hole portion 102a and long hole portions 102b extending on both opposing sides. Around the upper surface of the engagement hole 102, a recess 103 is formed into which the umbrella portion 4 of the obturator 1 is fitted.

The obturator 1 comprises a main body 2 that closes the engagement hole 102, and a locking mechanism 3 that is incorporated into the main body 2.

As best shown in Figures 1 and 13-15, the main body 2 comprises a roughly disk-shaped umbrella portion 4 that is placed on the upper surface of the manhole cover 101 to cover the engagement hole 102, and a cylindrical cylinder portion 5 that extends downward from the underside of the umbrella portion 4 through the engagement hole 102. A positioning protrusion 6 is provided on the underside of the umbrella portion 4 as a positioning engagement portion that regulates the mounting position of the cylinder portion 5 around the axis relative to the engagement hole 102.

As shown in Figures 1 and 3, from the top, a rotor 7, a weak pressure spring 8, a locking member 9, and a strong pressure spring 10 are assembled into the cylinder section 5 to form the locking mechanism 3.

The upper end of the cylinder section 5 opens onto the umbrella section 4 through a circular opening 11, and the lower end is closed by a bottom cover 12. The inner circumference is provided with a guide protrusion 13 for guiding the operation of the rotor 7, and the side wall is provided with a guide opening 14 for guiding the operation of the locking member 9.

As shown in Figures 1 and 6 to 21, the rotor 7 has a tool hook 15 at its upper end exposed from the circular opening 11 so that an operating tool (not shown) can be hung, and a cylindrical portion 16 continuing below the tool hook 15.

The rotor 7 can rotate around an axis between three positions relative to the main body 2: an unlocked position, a locked position 90° away from the unlocked position, and a fixed position 60° away from the unlocked position. Marks 11a to 11c indicating the unlocked, locked, and fixed positions of the rotor 7 are provided on the periphery of the circular opening 11, facing the mark 15a on the tool hook 15, allowing the relative rotational position of the rotor 7 and the main body 2 to be confirmed.

The rotor 7 can also move up and down between an upper blocking position where the tool hook 15 blocks the circular opening 11 and a lower depressed position where it is pushed into the cylinder section 5, and is biased to the blocking position by the low pressure spring 8 and fitted into the cylinder section 5.

The cylindrical portion 16 of the rotor 7 has a guide groove 17 on its outer periphery that engages with the guide protrusion 13, and an engagement portion 18 on its underside that consists of an annular row of teeth with a sawtooth cross section. The engagement portion 18 engages with the locking member 9 in the rotational direction when the rotor 7 is in the pressed-down position, and can rotate the locking member 9.

As shown in Figures 1 and 22 to 24, the locking member 9 has a crown portion 19 and a locking piece 20. The crown portion 19 has a corresponding engagement portion 21 on its upper surface, which is made up of a row of teeth with a sawtooth cross section arranged in an annular shape so as to be able to engage and disengage with the engagement portion 18 of the rotor 7.

The lock piece 20 extends radially outward from the radially opposing portion of the crown portion 19 and movably passes through the guide opening 14 of the cylinder portion 5.

The locking member 9 is rotated and driven up and down by the rotor 7 via the engagement parts 18, 21, and can rotate 90 degrees between an unlocked position (corresponding to the unlocked position of the rotor 7) where the locking piece 20 faces the long hole part 102b of the engagement hole 102, and a locked position (corresponding to the locked position of the rotor 7) where it is perpendicular to the long hole part 102b. It can also move up and down between a lower open position (corresponding to the pressed position of the rotor 7) and an upper abutting position (corresponding to the closed position of the rotor 7), and is biased to the upper abutting position by the strong pressure spring 10 and fitted into the cylinder part 5.

The guide groove 17 of the rotor 7 engages with the guide protrusion 13 of the cylinder portion 5 so as to be movable relative to the cylinder portion 5, and includes a first rotation guide groove 17c that extends from the first end 17a to the second end 17b at the upper end of the cylindrical portion 16 over a rotation angle of 90° in the horizontal direction (guiding the rotation of the rotor 7 between the unlocked position (11a) and the locked position (11b)), a vertical guide groove 17d that extends vertically downward from the second end of the first rotation guide groove 17c (guiding the raising and lowering of the rotor 7 between the pressed position and the closed position), and a second rotation guide groove 17f that extends horizontally from the lower end of the first rotation guide groove 17c over a rotation angle of 60° to the rotation end 17e in the opposite direction to the first rotation guide groove 17c (guiding the rotation of the rotor 7 between the locked position (11b) and the fixed position (11c)).

The guide opening 14 of the cylinder section 5, through which the locking piece 20 passes, guides the rotation and vertical movement of the locking member 9 relative to the cylinder section 5, and includes a rotation guide opening 14c that extends from the first end 14a to the second end 14b over a horizontal rotation angle of 90° (guiding the rotation of the locking member 9 between the unlocked and locked positions), and a vertical guide opening 14e that continues from the second end 14b and extends vertically upward to the lock end 14d (guiding the lifting and lowering of the locking member 9 between the open and closed positions).

The relationship between the operation of the cylinder portion 5, the rotor 7, and the locking member 9, and the relative positions of the guide protrusion 13, the guide groove 17, the guide opening 14, and the locking piece 20 is set as follows.

As shown in Figures 2 to 4 and 25, when the rotor 7 is in the unlocked position (11a) with the engagement portions 18, 21 with the locking member 9 engaged in the depressed position, the guide protrusion 13 of the cylinder portion 5 is in the retaining recess 17g at the first end 17a of the first rotation guide groove 17c of the rotor 7, the locking piece 20 of the locking member 9 is in the retaining recess 14f at the first end 14a of the rotation guide opening 14 of the cylinder portion 5, and is in an unlocked position where it can pass up and down through the long hole portion 102b of the engagement hole 102.

As shown in FIG. 26, when the rotor 7 rotates from the unlocked position (11a) to the locked position (11b) together with the locking member 9 in the depressed position, the guide protrusion 13 moves relatively from the first end 17a to the second end 17b of the first rotation guide groove 17c of the rotor 7, and at the same time, the rotor 7 rises together with the locking member 9 due to the biasing force of the springs 8 and 10, and the guide protrusion 13 moves relatively to the lower end of the upper and lower guide grooves 17d. During this time, the locking piece 20 of the locking member 9 moves from the first end 14a to the second end 14b of the rotation guide opening 14 of the cylinder portion 5 to reach the locked position, and at the same time, due to the biasing force of the springs 8 and 10, it rises to the lock end 14d of the upper and lower guide openings 14e and follows the rotor 7 to the abutting position.

As shown in Figures 5 to 7, when in the locked position, the lock piece 20 rises to the abutment position and clamps the outer edge of the circular hole 102a of the engagement hole 102 between the underside of the umbrella part 4, making it impossible to remove the obturator 1 from the engagement hole 102.

As shown in FIG. 27, when the rotor 7 rotates from the locked position (11b) to the fixed position (11c), the lock piece 20 of the lock member 9 is at the lock end 14d of the rotation guide opening 14 of the cylinder part 5, preventing the lock member 9 from rotating and stopping it at the locked position, while the guide protrusion 13 of the cylinder part 5 moves relatively from the lower end of the upper and lower guide grooves 17d of the rotor 7 to the rotation end 17e of the second rotation guide groove 17f, and the rotor 7 rotates independently to the fixed position while the engagement parts 18, 21 rotate freely due to the elasticity of the spring 8. When the rotor 7 is in the fixed position (11c), the lock member 9 maintains the locked position (FIGS. 9, 10, 27c), and the guide protrusion 13 of the cylinder part 5 is at the rotation end 17e of the second rotation guide groove 17f of the rotor 7, preventing the rotor 7 from being pushed down.

To attach the obturator 1 to the engagement hole 102, align the positioning protrusion 6 of the umbrella portion 4 with the long hole portion 102b in the state shown in Figures 2 to 4, and insert the cylinder portion 5 into the center of the engagement hole 102.

Next, the rotor 7 is pushed down with an operating tool to engage the engagement parts 18, 20, and then rotated 90° clockwise in FIG. 2, placing the rotor 7 in the locked position (11b) and the locking member 9 in the locked position, and then the rotor 7 is released. When the rotor 7 is released, the force of the strong pressure spring 10 pushes the locking member 9 in the locked position up along the vertical guide opening 14e (FIG. 26(c)), and the locking piece 20 is automatically pressed against the bottom surface of the hole edge of the engagement hole 102 (FIG. 6). Multiple rotation operations are not required. The locking member 9 is pressed against the bottom surface of the hole edge of the manhole cover 101 at an appropriate upper or lower position within the vertical guide opening 14e, so this obturator 1 can be universally applied to multiple types of manhole covers 101 with different hole edge thicknesses.

When the rotor 7 is rotated further from this state by 60° clockwise in FIG. 26 to the fixed position (11c), the lock piece 20 stops at the lock end 14d of the vertical guide opening 14e as shown in FIG. 27(c), while the rotor 7 rotates with the engagement parts 18, 21 rotating freely until the guide protrusion 13 follows the second rotation guide groove 17f and reaches the fixed end 17e. When the guide protrusion 13 is at the fixed end 17e, the rotor 7 is fixed in the vertical direction, so even if a pedestrian's thin heel or the like stands on the rotor 7, the rotor 7 does not collapse, and therefore the heel or the like does not get stuck in the opening 11 and become an obstacle to walking.

1 Obturator 2 Main body 3 Locking mechanism 4 Umbrella portion 5 Cylinder portion 6 Positioning protrusion 7 Rotor (locking mechanism)
8. Light pressure spring (lock mechanism)
9 Locking member (locking mechanism)
10. Strong pressure spring (lock mechanism)
11 Circular opening 11a Unlocking position mark 11b Locking position mark 11c Fixed position mark 12 Bottom cover 13 Guide protrusion 14 Guide opening 14a First end 14b Second end 14c Rotation guide opening 14d Lock end 14e Vertical guide 14f Holding recess 15 Operating tool hook portion 15a Position indication mark 16 Cylindrical portion 17 Guide groove 17a First end 17b Second end 17c First rotation guide groove 17d Vertical guide groove 17e Fixed end 17f Second rotation guide groove 17g Holding recess 18 Engagement portion 19 Crown portion 20 Lock piece 21 Engagement portion 101 Manhole cover 102 Engagement hole 102a Circular hole portion 102b Long hole portion 103 Recess

Claims (4)

A manhole cover has an engagement hole for inserting a cover-opening tool, the engagement hole being made up of a circular hole portion and long hole portions extending on both opposing sides of the circular hole portion. The manhole cover has an engagement hole for inserting a cover-opening tool, and the engagement hole is attached to the manhole cover to close the engagement hole,
A main body including an umbrella portion placed on an upper surface of the manhole cover so as to close the engagement hole, and a cylindrical cylinder portion extending downward from a lower surface of the umbrella portion so as to pass through the engagement hole;
The lock mechanism includes a rotor, a weak pressure spring, a lock member, and a strong pressure spring, which are assembled in the cylinder portion from above.
the umbrella portion includes a positioning engagement portion that regulates an attachment position of the cylinder portion around an axis relative to the engagement hole,
the cylinder portion has an upper end that is open on the umbrella portion by a circular opening and a lower end that is closed by a bottom cover, and has an inner periphery that is provided with a guide protrusion that engages relatively movably with a guide groove on the outer periphery of the rotor to guide the rotation about the axis and the vertical movement of the rotor, and a side wall that is provided with a guide opening that engages relatively movably with a lock piece of the locking member to guide the rotation about the axis and the vertical movement of the locking member,
the rotor is provided with a tool hanging portion at an upper end exposed from the circular opening so that an operating tool can be hung thereon, and a cylindrical portion continuing downward therefrom, and is rotatable about an axis within the cylinder portion among three positions, i.e., an unlocked position, a locked position, and a fixed position, and is movable up and down between an upper closing position in which the tool hanging portion closes the circular opening, and a lower depressed position in which the tool hanging portion is pushed into the cylinder portion, and is fitted into the cylinder portion while being biased to the closing position by the low pressure spring;
the cylindrical portion of the rotor is provided with the guide groove on its outer periphery, the guide groove including a first rotation guide groove for rotatably guiding the rotor to an unlocked position and a locked position 90° away from the unlocked position around the axis by engaging the guide protrusion, a vertical guide groove for guiding the rotor up and down from a pressed position to a closed position at the locked position, and a second rotation guide groove for rotatably guiding the rotor to a fixed position at an angle less than 90° away from the locked position at the closed position,
the cylindrical portion of the rotor has an engagement portion on its underside, the engagement portion being made up of a row of teeth arranged in an annular shape having a sawtooth cross section so as to be able to rotationally engage with the locking member in a pressed-down position to rotate the locking member 90° around an axis between an unlocked position and a locked position;
the locking member comprises a crowned portion having on its upper surface a corresponding engagement portion consisting of a row of teeth with a sawtooth cross section arranged in an annular shape so as to be engageable with and disengageable from the engagement portion of the rotor, and a locking piece extending radially outward from the crowned portion and movably passing through a guide opening of the cylinder portion, the locking member being driven by pushing and rotating the rotor between an unlocked position and a locked position, the locking piece being rotatable by 90° between an unlocked position in which the locking piece faces the elongated hole portion of the engagement hole along the guide opening and a locked position in which the locking piece is perpendicular to the elongated hole portion, the locking piece being movable up and down between a lower open position in which the locking piece is separated from the underside of the lid and an upper abutment position in which the locking piece is pressed against the underside of the lid, the locking member being biased to the abutment position by the strong pressure spring and fitted into the cylinder portion,
the guide opening of the cylinder portion includes a rotation guide opening that guides the lock piece from the unlocked position to a locked position 90° away from the axis at a lower open position, and a vertical guide opening that guides the lock piece upward and downward to an abutting position at the locked position,
A closure device for a manhole cover opening operating device engagement hole, characterized in that the weak pressure spring and strong pressure spring are compressed, the rotor is in the pressed position, unlocked position, and the locking member is in the open position, unlocked position, and is inserted into the engagement hole of the lid, and as the rotor is pushed around to the locked position, the locking member rotates to the locked position in conjunction with the rotor being pushed around to the locked position, and at the same time, the strong pressure spring rises together with the rotor to the abutment position, and when the rotor is further pushed around to a fixed position by rotating the engagement portion freely while keeping the locking member in the abutment position, the guide protrusion is positioned within the second rotation guide groove, thereby fixing the rotor in the vertical direction relative to the cylinder portion. The manhole cover opening operating tool engagement hole closure device according to claim 1, characterized in that the guide opening has a retaining recess at the top of one end of each rotation guide opening, which retains the lock piece in the unlocked position. The manhole cover opening tool engagement hole closure device according to claim 1, characterized in that the guide groove has a retaining recess at the lower part of one end of the first rotation guide groove with which the guide protrusion engages in the unlocked position, thereby retaining the rotor in the unlocked position. The manhole cover opening tool engagement hole closure device according to claim 1, characterized in that the guide groove has a retaining recess at the lower part of one end of the second rotation guide groove with which the guide protrusion engages in a fixed position, thereby holding the rotor in a fixed position.

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