JPS6317758B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] Accordingly, the present invention is directed to a crane such as a crawler crane, in which a lightning rod is provided at the tip of a boom, mast, etc. that is movably provided on the main body of a crane such as a crawler crane. This invention relates to a mobile crane equipped with a lightning arrester, and particularly to a crane equipped with a lightning arrester, in which a fixed position device is always set as a lightning arrester through a variable position device at the tip of the boom mast so that it is always pointed toward the sky. This is such an invention.

[Background of the invention]

As is well known, at construction sites, the weight and size of buildings and equipment being brought in tend to increase due to improvements in work efficiency and architectural design considerations, and as a result, the cranes used to lift them tend to become larger. I'm getting used to it.

As for cranes, there are fixed cranes and mobile cranes, but the latter mobile cranes have been widely used in terms of mobility and work efficiency, and as mentioned above, mobile cranes have also become larger. It's coming.

The latter mobile cranes include, for example, crawler cranes, truck cranes, wheel cranes, and floating cranes, but as mentioned above, these cranes are becoming more and more expensive due to the increase in construction size and lifting capacity. Masts are increasingly being used with large protrusions and protruding high into the sky.

Therefore, like general buildings, it has come to resemble a type of high-rise building, and there is a high risk of damage from lightning due to conditions such as the absence of surrounding high-rise buildings at the construction site. I'm getting used to it.

By the way, lightning strikes are influenced by the nature of the lightning, the strength of the thundercloud, the height of the terrain, the resistance to land transfer, and other natural environmental conditions, as well as the conditions of the building. Therefore, the possibility of being struck by lightning is high in areas where lightning strikes occur frequently, and in order to deal with this, as mentioned above, the larger the crane, the more it becomes necessary to consider lightning protection measures.

Therefore, lightning protection towers are generally installed in some cases to cover the entire construction site, but there is a problem in that the lightning protection effect is not sufficient for mobile cranes.

The mechanism of lightning generation is generally extremely complex and not fully understood, but in terms of phenomena, upward streamers are generated from the tips of protrusions on the ground, and downward streamers are generated from thunderclouds. There are two phenomena.

Therefore, the former can be avoided by installing a lightning rod at the tip of a steel tower, etc., but the latter cannot be sufficiently effective as lightning protection for mobile cranes.

This is because a mobile crane has a wide working radius and is flexible, so it may deviate from the lightning protection area of the lightning protection tower.

In response to this problem, cranes equipped with lightning arresters have come to be used by attaching lightning arresters to the tips of crane booms, etc.

Therefore, a conventionally used crane 1 with a lightning protection device will be briefly explained based on FIG. 1. A cradle 4 having a driver's cab 3 is rotatably provided on a crawler 2 serving as a pedestal. A mast 6 having a support pin 5 is provided on the pedestal 4, and a boom 7, which is also provided on the pedestal 4 so as to be able to raise and lower freely, is connected to a pulley 8 on the mast 6.
The equipment 11 is operated by a winch 9 provided on the pedestal 4 via a wire 10 in a manner that it can be raised or lowered freely. The frame 4 is raised and lowered via a winch 15 of the frame 4 by a wire 14 via a pulley 13 provided at the frame 4 .

Therefore, when the crane 1 is operated, the lightning arrester 16 moves between the highest level 17 and the lower level 18 as the boom 7 rises and falls, as shown in FIG.

The protection range of the lightning rod 16 is the area 18 shown by the hatching in FIG. Although the embodiment in which the lightning rod 16 is attached is effective, the protection angle becomes narrow at the lower level 18, so the lightning rod 16
It is necessary to compensate for this by providing a plurality of , which has the disadvantage of complicating the structure.

In addition, at the lower level 18, as shown in the figure, the wires 10 and 14 are out of the protection range of the lightning rod 16, so if a downward streamer from a thundercloud occurs, the probability of being struck by lightning is extremely high. However, there was also the problem that if the wires 10 and 14 were struck by lightning, a serious accident could occur.

In addition, as a lightning protection measure, the lightning rod 16 is installed based on the information from the lightning strike prediction device, taking into account the scale of the construction site, the aforementioned natural environment conditions, or the observation data of past lightning strikes at the construction site. In order to raise and lower the boom 7 to a position where the crane faces toward the sky, the boom 17 must be raised and lowered, and as the crane 1 becomes larger, the lowering and lowering motion becomes slower, which increases the time required and requires energy. There was also this problem.

[Purpose of the invention]

The object of the present invention is to solve the problems of the lightning arrester of a mobile crane based on the above-mentioned prior art, and to make the lightning arrester always have an upward attitude, and to cover the entire crane with lightning protection. It is an object of the present invention to provide a crane with an excellent lightning protection device that will benefit the field of crane use in the construction industry.

[Summary of the invention]

A mobile crane with a lightning arrester according to the present invention is a mobile crane in which a lightning arrester is provided at the tip of a boom movably provided on a crane body, wherein the lightning arrester is fixed to the tip of the boom. an arm, a pin provided laterally on the arm, a bar fitted rotatably about the pin, a lightning rod provided at the tip of the bar, and a heavy hanging provided at the bottom of the bar. A lightning arrester is characterized in that it is equipped with a lightning arrester fixing position device consisting of:

In the present invention, a variable displacement device is provided at the tip of the boom or mast of a mobile crane, and a lightning rod is provided on the variable displacement device via a fixed position device, so that a streamer is generated as it moves from a protrusion on the ground toward a thundercloud. Of course, even when a streamer is generated from a thundercloud toward the ground, the lightning arrester attached to the fixed-position device always points towards the sky, regardless of the angle of the boom. In addition, an overhead ground wire that follows the wire that moves the boom up and down is stretched between the boom and the mast to cover substantially the entire crane with lightning protection. Technical measures have been taken to achieve this goal.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described below based on the drawings from FIG. 3 onwards. Note that the same parts as in FIGS. 1 and 2 will be described using the same reference numerals.

In the embodiment shown in FIGS. 3 to 6, the crane 1
The boom 7 installed on the pedestal 4 on the crawler 2, the mechanical parts such as the mast 6, and the mechanism of the up-and-down movement thereof are all substantially the same as the conventional configuration shown in FIGS. 1 and 2 above. By operating the driver's cab 3, the boom 7 is raised and lowered between a highest level 17 and a lower level 18 to perform predetermined mobile construction work.

As shown in FIGS. 4 and 5, an arm 2 as a variable displacement device is attached to the tip of the boom 7 and the mast 6.
0 is fixedly extended at a set angle, and a pin 21 serving as a fixed posture device is provided laterally at the tip thereof. A bar 2 serving as a lightning arrester has a lightning arrester rod 16' fixed to the upper part of the pin 21 and a heavy drop 22 of a predetermined weight fixed to the lower part thereof.
3 is pivotally supported on the pin 21 so as to be relatively rotatable.

Therefore, regardless of the ups and downs of the boom 7 and the mast 6, the bar 23 as a lightning arrester provided at the tips of them, that is, the lightning arrester rod 16' should always have its tips pointed vertically toward the sky as shown in the figure. is made possible.

An unillustrated cable connected to the bar 23 is used to insulate the crane 1 from excessive current that has struck the lightning rod 16' and to ground it.

Of course, the cable is covered with a safety cover as a safety measure for workers.
Further, the cable is connected to the arm 20 of the boom 7.
The tip is fixed to , and the wire is wound up via a pulley 24 provided on an arm 20 at the tip of the mast 6 onto a rotatable take-up drum 25 provided on the pedestal 4 and equipped with a function to prevent generation of swirling current.

For example, an overhead ground wire 26 made of copper wire or the like is inserted between the boom 7 and the mast 6 as shown in the figure, and adjusted so that a triangle is formed on the same plane.
The overhead ground wire 26 is connected to the boom 7 with a ground 28 connected to the drum 25 via a socket 27.
Regardless of the ups and downs of the boom 7, the lightning protection cover range 19 always covers substantially the entire crane 1, as shown in FIG. I have made it possible to do so.

In the above configuration, the crane 1 moves the wire 1 at a predetermined construction site using its crawler 2.
0 and 14, the boom 17 is raised and lowered between the highest level 17 and the lower level 18,
Further, the equipment 11 is lifted up and lowered while rotating the pedestal 4 with respect to the crawler 2, and is used for predetermined construction work.

As mentioned above, at the work site, when dealing with a lightning strike based on lightning strike prediction information, etc., the boom 7
Even if a streamer from the sky to the ground or from the ground to the sky occurs, the bar 23 of the lightning arrester installed at the tip of the boom 7 and the mast 6 will be protected by the heavy suspension 22 even if the streamer does not collapse immediately. It rotates around the pin 21 and is always directed vertically toward the sky with the lightning rod 16', so even if there is a lightning strike, the excess current will be reliably grounded by the insulated cable and sent to the crane 1. There will be no lightning strikes.

In addition, since the overhead ground wire 26 stretched between the boom 7 and the mast 6 is always covering the crane 1 and being grounded, the crane 1 is always within the lightning protection coverage area 19.
range, so you are always safe from lightning strikes.

When the lightning arrester 16' is at the highest level 17 as shown in FIG. Only a portion of the lightning protection coverage area is set to 19 range.

However, since the overhead ground wire 26, which expands and contracts following the wires 10 and 14, is extended and contracted between the boom 7 and the mast 6 as one side of a triangle on the same plane that includes both, the lower level 18 Even in this case, the crane 1 can be substantially contained within the lightning protection coverage range 19.

In the above-described embodiment, the bar 23 of the lightning arrester rotates in a plane with respect to the flexible pin 21, but it is mounted on a ball bearing or the like and can be freely displaced three-dimensionally to form the lightning arrester 16' to change the posture of the crane 1. It is easy to change the design so that it always points vertically toward the sky regardless of the situation.

In addition, as mentioned above, the probability of a lightning strike occurring is high depending on the natural conditions such as the topography, land concession conditions, weather, etc., and the design conditions of buildings, etc., but it is also important to consider the probability of a lightning strike based on past experience. Therefore, at a design construction site, it is possible to employ a crane 1 that does not require the above-mentioned overhead ground wire 26 to be stretched, depending on the case.

In such a case, as in the embodiment shown in FIG. 7, the lightning arrester overhead ground wire 26 is simply provided at the tips of the boom 7 and the mast 6 via a fixed position device and a variable displacement device. It is also possible to use a mode in which the wire is not stretched.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments; for example, the overhead ground wire may be extended or contracted to follow the wire freely by a heavy hanging instead of a drum winch. Various aspects can be adopted, such as being able to do the following.

Further, as a design change, for example, the above-mentioned overhead ground wire has one strip in the illustrated embodiment, but it is also possible to have multiple strips, and instead of providing the lightning arrester and the ground for the overhead ground wire separately. It is also possible to combine both of them.

The lightning prediction device is installed on the mount, or
It is also possible to install it at the tip of the boom.

〔Effect of the invention〕

As described above, according to the present invention, the lightning protection function can be maintained at all times regardless of the working range of the mobile crane and regardless of the ups and downs of the boom, and the lightning protection coverage area is always maintained. Since the crane can be covered, there is no need for the conventional work of moving the crane to lightning protection or lowering the boom in preparation for lightning strike prediction, and the time required for doing so is also not wasted. This has the excellent effect of improving crane operating efficiency, shortening the construction period and reducing man-hours.

Another advantage is that sufficient work can be carried out safely without being affected by the accuracy of lightning strike prediction.

Therefore, by installing a fixed position device at the tip of the mobile crane's boom mast to always direct the lightning rod vertically to the sky via a variable displacement device such as an arm, it is possible to maintain the vertical position. Regardless of the up-and-down position of the boom, the lightning rod always faces vertically toward the sky, which has the excellent effect of always fully exerting the function of the lightning rod against the streamer phenomenon in which lightning is fired from the ground toward the thundercloud. is played.

On the other hand, even if the lightning rod cannot cover the streamer phenomenon that occurs from thunderclouds toward the ground, the overhead ground wire can sufficiently compensate for the area, so if both are installed, The crane can always be within the lightning protection coverage area and work can be carried out safely, which is an excellent effect.

In addition, if the construction work is large-scale, or a large structure is constructed in a remote area, mountainous area, or newly developed area, and there is no accumulation of lightning prediction information for the construction site, if the crane is large, The more it is, the better the effect can be exhibited.

In addition, even if the device is an existing device or a large crane that has been scaled up, a simple structure lightning arrester can be attached to the tip of the boom mast, and an overhead ground wire can also be installed on the boom mast. Therefore, the structure is not complicated and assembly is easy.
Another advantage is that it can be done at low cost.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a crane equipped with a lightning arrester based on the prior art, Fig. 2 is an explanatory diagram of the lightning protection coverage range, and Fig. 3 and the following are explanatory diagrams of embodiments of the present invention. A side view of the embodiment, FIG. 4 is the third
Figure 5 is a partially enlarged side view; Figure 5 is a sectional view of Figure 4;
This figure is an explanatory diagram of the lightning protection coverage range in FIG. 1, and FIG. 7 is an explanatory diagram corresponding to FIG. 6 of another embodiment. 1...Crane, 7...Boom, 16'...Lightning rod,
20... Arm, 23... Bar, 26... Overhead ground wire, 1
8...Earth.

Claims (1)

[Claims] 1. In a mobile crane in which a lightning arrester is provided at the tip of a boom movably mounted on the crane body, the lightning arrester is provided on an arm fixed to the tip of the boom and horizontally on the arm. A lightning rod fixing position device is provided, which includes a pin, a bar fitted so as to be rotatable about the pin, a lightning rod provided at the tip of the bar, and a hanging provided at the bottom of the bar. A mobile crane with a lightning arrester, characterized in that it is a lightning arrester.