JPH0131624Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application The present invention relates to a key stick for opening and closing a manhole iron cover (hereinafter referred to as the key stick), which is used to open and close a manhole iron cover installed on a road surface, etc. .

Prior Art A conventional key stick K is shown in FIG. Insert the key stick K shown in Fig. 3 into the keyhole 4 of the manhole iron cover F shown in Fig. 4, rotate the inserted key stick K 90 degrees, and support the manhole iron cover F with the key stick K. In the operation of supporting the manhole iron cover with the support part 5 and opening and closing it, the back surface 6 of the manhole iron cover F shown in FIG. 5 and the upper surface 7 of the key bar manhole iron cover support part 5 are in surface contact. When the back surface 6 of the manhole iron cover F is uneven, or when manhole iron, earth and sand, or pebbles are mixed in, there is a possibility that the load will be applied to the tip 8 of the key bar manhole iron cover support part 5. . In this case, the bending moment at the base 9 of the key bar manhole iron cover supporting portion 5 is maximum, and the breaking load of the key bar K is a low value. For this reason, the allowable limit of the load that can be applied when the key stick K opens and closes the manhole iron cover becomes smaller, and in order to compensate for this, the wall thickness of the manhole iron cover support part 5 of the key rod K is made thicker in the axial direction. As shown in Figure 6, there is an inner cover 10 under the manhole iron cover, and it cannot be used if there is insufficient space for inserting the key bar manhole iron cover support part 5 between the inner cover top surface 11 and the manhole iron cover back surface 6. There are drawbacks.

Problems to be Solved by the Invention In the present invention, even if dirt or pebbles are mixed in, the load of the manhole cover is always applied to the base of the key bar manhole cover support, increasing the failure load value.

Means to Solve the Problem The present invention fixes a separate key body fixing part on the top of a cylindrical shaft part, and fixes the key hole of a manhole iron cover, which is a plate-shaped body protruding linearly from side to side at the bottom. In the key rod for opening/closing a manhole cover, which is provided with an integrally formed manhole cover support that can be inserted into the manhole cover, the side surface of the manhole cover support is formed into a tapered part that rises from the end toward the shaft.

Function: With the above-mentioned configuration, the present invention can always support the load of the manhole cover at the base of the manhole cover support, and can withstand extremely large opening and closing forces of the manhole cover without being damaged.

Embodiment FIG. 1 shows a front view of the key stick of the present invention, and FIG. 2 shows a bottom view of the same as seen from below.

In the figure, P indicates the key stick of the present invention, 1 indicates the key body fixing part, 2 indicates the shaft part, and 3 indicates the manhole cover support part.

The structure of the key stick of the present invention will be explained.

The shaft part 2 is a cylindrical rod, and a ring-shaped key body fixing part 1 provided separately on the upper part is fixed to the shaft part 2 by an appropriate means, and the lower part can be inserted into the keyhole 4 of the manhole iron cover F. A support part 3 whose cross-sectional shape is similar to that of the keyhole 4 and integrally protrudes on the left and right sides is provided, and the shape of the key stick F is formed into a hammer shape, and one of the support parts 3 is raised in the axial direction from the end. A tapered portion is provided, and a portion near the shaft portion 2 is formed in an arc shape concave outward.

How to use the key stick F of the present invention will be explained.

Insert the invented key stick P into the manhole iron cover keyhole 4 from the manhole iron cover support part 3, and when it is fully inserted, rotate the key stick P 90 degrees and pull the key stick P upward, as shown in Fig. 7. As shown, the base 9 of the key bar manhole iron cover support part 3 is connected to the back side 6 of the manhole iron cover.
and supports the manhole iron cover F. Further, when the key stick P is pulled up by operating a key (not shown), the manhole iron cover F is lifted up and opened/closed.

The key stick P of the present invention has a structure in which the manhole iron cover supporting part 3 has a tapered shape and is loaded on the base part 9 of the strong manhole iron cover F, so that the opening and closing force of the manhole iron cover 4 is very large. It can withstand damage without being damaged.

Figure 8 shows damage when the conventionally used key rod and shaft portion 2 have the same shape and the wall thickness of the manhole iron cover support portion is the same as the wall thickness a of the manhole iron cover support portion 3 of the key rod of the present invention. It is a load. In the key stick K having a conventionally used shape, the breaking load decreases from the base 9 to the tip 8 of the manhole iron cover support 5.

On the other hand, the key rod P of the present invention is loaded only on the base 9 of the manhole iron cover support part 3, and at this time, the failure load of 12 shown in the diagram is approximately 9 tons, and the tip 8 of the conventional manhole iron cover support part 5. In the worst case, the failure load 13 applied to the vehicle was approximately 2.9 tons, which was three times greater.

Effects of the invention As explained above, the key rod of the invention has a tapered shape when viewed from the side of the manhole cover support.
The load applied when opening and closing the manhole iron cover is concentrated on the base of the manhole iron cover supporting part to increase the strength and making the wall thickness of the manhole iron cover support part as thin as possible. Therefore, even a manhole cover with a small insertion space for the manhole cover supporting portion between the back surface of the manhole cover and the top surface of the inner cover can be opened and closed.

[Brief explanation of drawings]

Fig. 1 is a front view of the key stick of the present invention, Fig. 2 is a bottom view of the key stick of the present invention, Fig. 3 is a front view of a conventional key stick, Fig. 4 is a plan view of the manhole iron cover, Figure 5 shows a conventional key rod inserted into a manhole iron cover.
Figure 6 is a diagram of the manhole iron cover being inserted into the manhole iron cover receiving frame, Figure 7 is a diagram of the key rod of the present invention being inserted into the manhole iron cover keyhole, and Figure 8 is a diagram of the conventional key rod manhole iron. A relationship diagram between the distance from the base of the lid support and the breaking load of the key rod is shown. P... Key stick, 1... Key body fixing part, 2... Shaft part, 3... Manhole iron cover support part, a... Thickness of base of manhole iron cover support part, F... Manhole iron cover, 4 ...Keyhole, 5...Key bar manhole iron cover support, 6...Back side of manhole iron cover, 7...Top surface of manhole iron cover support, 8...Tip of manhole iron cover support, 9...Key bar The base of the manhole cover support.

Claims (1)

[Scope of utility model registration request] A separate key body fixing part is fixed to the upper part of the cylindrical shaft part, and the manhole iron cover support is integrally formed so that it can be inserted into the keyhole of the plate-shaped manhole iron cover that projects linearly left and right at the lower part. The key rod for opening and closing a manhole iron cover is provided with a manhole iron cover opening/closing key, in which the side surface of the manhole iron cover support part is formed into a tapered part rising from the end in the axial direction.