JPS6056679B2 - Mooring device for offshore floating bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for mooring a floating body on the sea at a predetermined position, and more particularly to a mooring device that reduces impact force acting on a mooring chain or link due to movement of the floating body.

Typically, a floating body moored at sea (such as a floating runway, submarine drilling rig or pipelay barge)
When repeated external forces are applied due to waves, wind, earthquakes, etc., especially when the force is close to the resonance frequency of the floating body, the mooring stress due to resonance may become excessive and cause damage to the mooring chain or link. .

In order to absorb such vibrations and reduce shocks, if a floating body is moored via an air-hydraulic cylinder device for regulating the neutral position disclosed in Japanese Utility Model Publication No. 42-10291,
This avoids the dangers such as damage mentioned above, but due to the mechanism of this cylinder device, it is difficult to change the shock absorbing characteristics, and depending on the mooring conditions, it may not be possible to meet the required shock absorbing characteristics. .

Therefore, the present invention has been developed to buffer relatively small impacts with a good response, and to prevent the mooring force and amplitude from increasing even in the case of excessive external forces in abnormal situations, thereby preventing damage to the mooring means and stabilizing the floating body. The purpose is to provide a mooring device that can improve the

Examples of the present invention will be described below.

As shown in FIG. 1 or 2, the present invention includes a mooring means 3 such as a mooring chain, a wire, a link, etc. that connects a floating body 1 and a fixing device 2, and a mooring means 3 that connects a floating body 1 and a fixing device 2, and a and a damper 4 interposed therein.

In Fig. 1, a damper 4 is directly interposed between the mooring link 3a and the floating body 1, but in Fig. 2, the mooring wire 3b
is connected to a winch 5 attached to the floating body 1, and the other end of a wire 7 connected to a movable pulley 6 for adjusting the tension of this mooring wire 3b is tied to a damper 4, that is, the damper 4 is indirectly interposed. In any case, when the floating body 1 receives an external force and causes a movement, the damper 4 expands and contracts to absorb and relieve the force.

The damper 4 is constructed as shown in FIG.
, B, the first free pistons 10A, 10B, respectively.
are arranged so that they can slide freely.

A piston rod 11 is provided to freely slide through the free piston 10B and the cylinder end wall on the right side of the figure, and the piston rod 11 is integrally formed with a large-diameter collar 12 and a small-diameter column head 13. has been done. Hydraulic chambers A, b are formed concentrically in the axial direction inside the first free pistons 10A, 10B, and second free pistons 15a, 15b are housed in the hydraulic chambers A, b, respectively, so as to be able to slide freely. be done.

The piston rod 11 freely slides through the center of the second free piston 15b as well as the first free piston 10B. Note that the column head 13 of the piston rod 11
passes through the other first free piston 10A and comes into contact with the second free piston 15a inside the hydraulic chamber a.

However, since the inner diameter of this penetrating portion is smaller than the inner diameter of the hydraulic chamber a, the free piston 15a does not come out. The intermediate chamber 14 sandwiched between the first and second free pistons 10A and 10B is arranged within the above-mentioned limit so that the opposite surface on which hydraulic pressure acts on each of these free pistons is released to atmospheric pressure or low hydraulic pressure. It is connected to a communication path 16 with the outside provided in the wall 9.

Next, the first hydraulic chambers A and B communicate with each other in a passage 18 via ports 17A and 17B formed in the hydraulic cylinder 8,
The hydraulic pressure of an accumulator 21 is transmitted to this passage 18 via an orifice 19 and a check valve 20 arranged in parallel. In this case, for the flow from the hydraulic chambers A and B to the accumulator 21, the check valve 20 is opened 4 to smoothly send the hydraulic oil, and for the flow in the opposite direction, the orifice 19 causes a throttling action. .

Said second hydraulic chamber A. l5b are orifices 22a and 22a formed in the first free pistons 10A and 10B, respectively.
22b and check valves 23a, 23b parallel to this
When the hydraulic chambers A and B contract, the hydraulic oil flows out through the orifices 22a and 22b, and when they expand, the hydraulic oil flows out through the check valve 23a.
, 23b, the hydraulic oil smoothly flows in.

Here, the pressure receiving area of each piston is increased by an amount equivalent to the cross-sectional area of the piston rod 11 on the free piston 10B so that the first free pistons 10A and 10B are equal to each other.
The effective outer diameter of the second free piston 15a and 15b is expanded in the same way.
5b is formed to have a large diameter.

Furthermore, when the piston rod 11 moves to the left from the illustrated position, the column head 13 moves toward the second free piston 15.
a, and then after a predetermined stroke, the collar 12 pushes the first free piston 10A.

At this time, the second free piston 15b and the piston rod 1
The first large-diameter collar 12 is removed, and as a result, the second free piston 15b remains in the hydraulic chamber b. On the other hand, when moving to the right, the collar 12 is moved to the second free piston 15b.
When the stroke end is reached, the first free piston 10B is also moved integrally. At this time, the column head 13 of the piston rod 11 separates from the second free piston 15a, and the free piston 15a remains in the hydraulic chamber a in the first free piston 10A.
The present invention is configured as described above, and will be described in more detail below, including its operation.

The piston rod 11 of the damper 4 is connected to the mooring link 3 described above.
a or a wire 7, and when the floating body 1 receives an external force such as waves or wind and causes movement, an acting force is generated that pushes or pulls the piston rod 11 depending on the direction.

When the acting force is small, the tension of the mooring link 3a or the wire 7 is kept constant by the restoring force of the damper 4, and the floating body 1 is kept stationary at a predetermined position.

This is caused by the set pressure oil supplied to the hydraulic chambers A and B via the accumulator 21, which causes the first free piston 10A to
, 10B are both pressed until they come into close contact with the limiting wall 9,
Furthermore, check valves 23a and 23b are connected to hydraulic chambers A and b.
The pressure oil flowing through the second free piston 15
a and 15b are pushed to the low pressure side end, and in this state, the piston rod 11 is sandwiched between the second free pistons 15a and 15b from left and right to hold it in the neutral position shown in the figure, and this hydraulic pressure is broken. Outside of just that. Piston rod 11 only when a force acts on piston rod 11
moves in either direction. If an external force is applied to move the piston rod 11 to the right, the second free piston 15b will first move integrally with the piston rod 11 while contracting the hydraulic chamber b. At this time, the pressure in the hydraulic chamber b becomes higher than that in the hydraulic chamber B due to the throttling action by the orifice 22b, and the free piston 15b
acts in opposition to.

Therefore, if the external force acting on the piston rod 11 is within this range, only the second free piston 15b operates to alleviate and absorb the impact by the orifice 22b.

Next, when a greater external force is applied and the free piston 15b reaches the stroke end, the first free piston 10B also starts to move integrally.

Since the first free piston 10B has a larger pressure receiving area than the second free piston 15b,
Its shock absorption properties become significantly increased.

As the free piston 10B moves to the right, the hydraulic fluid in the hydraulic chamber B is returned to the accumulator 21 via the check valve 20, increasing the pressure in the accumulator 21, and the counterforce of the shock increases in proportion to the return resistance pressure at this time. .

Therefore, when a force close to the resonance frequency is applied to the floating body 1, the first free piston 10B acts to absorb it within its operating range, and in this way, the impact force can be compared. It can effectively buffer targets from small to large ranges with excellent responsiveness.

Note that when the free pistons 10B, 15b move, low pressure oil (or atmosphere) freely flows into the intermediate chamber 14, so the intermediate chamber 14 becomes negative pressure and the free pistons 10B, 15b move.
It does not inhibit the movement of 15b.

Also, at this time, the free piston 10A of the other hydraulic chamber A
and 15a are kept pressed against the limiting wall 9 by the hydraulic pressure generated by the accumulator 21.

Next, when the external force acting on the piston rod 11 is buffered and its movement stops, the free piston 10B is pushed back by the hydraulic pressure acting on the hydraulic chamber B, and the free piston 10B is pushed back via the check valve 23b. Since the free piston 15b is also pushed by the hydraulic pressure flowing into the piston rod 11, the piston rod 11 starts returning to the neutral position.

This return movement can be properly controlled by the squeezing effect of the hydraulic oil by the orifice 19, so that it returns to the neutral position in a stable state without causing sudden repulsion.

By the way, even if an acting force acts on the piston rod 11 in the opposite direction to the above, the free pistons 10A, 1 on the opposite side
It will be easily understood that the movement of 5b absorbs shock in exactly the same way.

In this way, the same buffering effect is exhibited against external forces from either the compression side or the expansion side, but the pressure receiving areas of the first and second free pistons 10A, 10B and 15a, 15b,
By appropriately selecting the effective stroke, the capacity, pressure, etc. of the accumulator 21, it is possible to adjust to the optimum state according to the demand. Incidentally, FIG. 4 shows the damping characteristics of the Gunpa 4 of this embodiment, but the first free pistons 10A, 10
It can be seen that the slope of the damping characteristic curve changes between the operating region B and the operating region of the second free pistons 15a and 15b.

As described above, according to the present invention, since two sets of free pistons with different pressure receiving areas are provided, the mooring force necessary to keep the floating body stationary under normal conditions can be exerted, and excessive external force can be avoided during abnormal conditions. It can effectively alleviate and absorb the impact when it occurs, and improves its durability by reducing the mooring stress and amplitude acting on the mooring means as much as possible, while also keeping the floating body stable at all times. It has the effect of being able to hold the mooring.

[Brief explanation of the drawing]

1 and 2 are general schematic diagrams of the mooring device of the present invention, FIG. 3 is an enlarged sectional view of the damper, and FIG. 4 is a diagram of its damping characteristics. 1...Floating body, 2...Fixing device, 3...
...Mooring means (wire, link), 4...
Damper, 8...Hydraulic cylinder, 10A, 10B
......First free piston, 11...Zeston rod, 15a, 15b...Second free piston, 19...Check valve, 20.
... Orifice, 21 ... Accumulator, 22
a, 22b... Orifice, A, B... First hydraulic chamber, A, b... Second hydraulic chamber.

Claims (1)

[Claims] 1 Consists of a mooring means that connects a floating body and a fixing device, and a damper that is directly or indirectly interposed in the middle of this mooring means, and this damper is slidably attached to a hydraulic cylinder that has a restricting wall in the center. A pair of first free pistons arranged opposite to each other, a second free piston coaxially arranged inside these free pistons, a hydraulic chamber for applying hydraulic pressure of an accumulator to each of these free pistons, It consists of an orifice that controls the operating speed of the free piston, and a piston rod that moves under the action of an external force and displaces the first free piston against hydraulic pressure when the second free piston moves a predetermined stroke. Features: A mooring device for marine floating bodies.