GB2328929A

GB2328929A - Collision detection device

Info

Publication number: GB2328929A
Application number: GB9819216A
Authority: GB
Inventors: Sami Skippari
Original assignee: KCI Konecranes International Oy
Current assignee: Konecranes PLC
Priority date: 1997-09-08
Filing date: 1998-09-04
Publication date: 1999-03-10
Anticipated expiration: 2018-09-04
Also published as: FI102827B1; AT411356B; JPH11157776A; FI973625A0; NO322512B1; ATA150598A; DE19840909A1; NO984114D0; FI102827B; NO984114L; GB9819216D0; DE19840909B4; JP3860920B2; GB2328929B

Abstract

A collision detection device for arresting the movement of a crane upon collision with an obstacle comprises a plough 3, pivotally linked to the front or rear of a crane at a first linking point 7, a limit switch 13, and first 15 and second 16 forcing means which engage the plough with the limit switch. When either forcing means is opposed, i.e. by a collision between the plough and an obstacle, the plough is disengaged from the limit switch resulting in a cessation of the cranes movement. Preferably the plough consists of an upper member 4 and a lower member 5, the upper member being rotatably mounted on the crane body at the first linking point and the lower member being rotatably mounted, in an opposite sense, on the upper member at a second linking point 10 such that only the lower member may collide with an obstacle. Preferably the first forcing means acts between the upper member and the crane and the second forcing means acts between the upper and lower members. Preferably either forcing means may be a spring (16, Figure 5) or a counterweight (115, Figure 5).

Description

i 2328929 1 SAFETY ARRESTING DEVICE OF A CRANE

BACKGROUND OF THE INVENTION

The invention relates to a safety arresting device of a crane for stopping the crane by the effect of an obstacle in the crane's path, the safety arresting device comprising a plough structure linked in its upper part to the crane, in the front andlor rear of said crane, the plough structure being forced into switching, by means of forcing means, to a limit switch that allows or prevents the motion of the crane, whereby in a normal situation and said switching being implemented, it is possible for the crane to move, but when an ob- stacle in the path diverts the plough structure against the force of the forcing means, off the said switching, the crane is prevented from moving.

The currently used safety arresting device solution has caused several problems and accidents with ship cranes, as a crew member may be standing on or between hatches of the ship, when the crane goes by, and consequently the person in question may be trapped between the safety arresting device and the hatch. The point of the safety arresting device that hits the person may be so high up that it takes a considerable force to trip the safety arresting device, which causes bodily injuries to th& person. Some shipping companies have had several accidents of this kind.

Another problem is the operation of the safety arresting device in one direction only. In several cranes, a ladder leading to the crane cabin is placed between the safety arresting device and the-body part of the crane, which may cause dangerous situations when people move about in this area while the crane is in use. Moreover, the safety arresting device may be dam- aged after catching in tools, for instance, since the safety arresting device turns in one direction only.

BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to provide an improved safety arresting device by means of which the above-described problems and dangerous situations can be eliminated. This is achieved with a safety arresting device of the invention which is characterized in that the plough structure has a second linking point located below the abovementioned linking point, and second forcing means by means of which the plough structure is also forced into switching to said limit switch, and against whose force the limit switch is disconnected from the switching that allows the crane to move, when an ob- 2 stacle that is in the crane's path in the direction of motion, in front of the plough structure, mainly hits between the first and the second linking point and slightly above the second linking point, or when an obstacle. between the plough structure and the crane hits below the second linking point, on the other hand, said limit switch being arranged to be disconnected against the forcing means from the switching that allows the crane to move, when an obstacle that is in the crane's path in the direction of motion in front of the plough structure mainly hits below the second linking point of the plough structure or within the area of the second linking point, whereby turning in relation to the first linking point is opposite to turning in relation to the second linking point.

The invention is simply based on adding a second linking point, whereby a drawback appearing in previous solutions can be eliminated, that is the increase of the force required for tripping the safety arresting device the higher up, i.e. the closer to. a linking point the hitting point is located in the plough structure, since in the present invention, due to the second linking point a collision mainly occurring within the whole area between the first and the second link trips the limit switch, and the force required for tripping can be adjusted sufficiently weak, so that the switch trips considerably more easily than in a structure with one link, also above the second linking poirit, relatively close to it.

For instance, springs, counterweight structures or similar solutions can be used as forcing means.

The use of two linking points improves the oI5erational safety considerably. The strongest force required for tripping the safety arresting device is needed exactly at the second linking point. This point is preferably positioned at the shoulder level of a person standing on the deck in front of the crane. Below or above this level, the weaker the force required for the operation of the safety device and for the arrest of the crane the more the distance grows upwards or downwards from this linking point, as the leverage grows.

The safety arresting device of the invention is not liable to breakage either, since the plough structure may turn in two directions due to its operating principle.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which 3 Figure 1 is a side view of a safety arresting device of the invention in its operational environment, Figure 2 is a front view of the safety arresting device of Figure 1, Figures 3 and 4 illustrate the safety arresting device of previous figures in various collision situations, and Figure 5 illustrates an alternative embodiment of the safety arresting device of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to Figures 1 and 2, the safety arresting device of the invention for stopping the crane by the effect of an obstacle in its path, cornprises a vertical plough structure 3 which is linked in its upper part by means of a suspension part 2 to the front (or correspondingly, to the rear or to both ends) of the schematically illustrated crane that is indicated by the reference numeral 1. This plough structure 3 consists of two elements 4 and 5. An up- per, first element 4 consisting of two beam structures that are laterally spaced from each other, is linked in its upper end to said suspension part 2 by means of links 7 in such a way that it may revolve about an axis that is transversal in relation to the crane 1. A second, ladder- like element 5 consisting of vertical beams 9 and transversal beams 9, is linked by means of links 10 to the upper element 4, which second element may likewise revolve about the axis that is transversal in relation to the crane 1, and which extends in this example nearly throughout the entire plough structure 3 vertically (the height of the element 5 is naturally selected to meet the need, to equal the entire plough structure 3, if necessary). The second plough element 5 is located outermost with respect to the crane 1 and it is the actual part that comes into contact with the obstacle. The first element 4, measured from top, extends to about the middle of the second element 5, and the linking point (links 10) of these elements 4 and 5 is located slightly higher up than the middle of the second element, preferably at the shoulder level of the person (not shown) in the crane's path. The above- mentioned obstacle in the path refers to all obstacles that are above the ground 11 within the area of the element 5.

A limit switch 13 that allows or prevents the motion of the crane is arranged in the upper part of the safety arresting device, Le. in an arm 12 protruding from the suspension part 2, which limit switch allows the crane to move in a normal situation, i.e. in this example, when coupled to a coupling part 14 of the second element 5 of the plough structure 3, but prevents the crane from 4 moving, i.e. Stops it, when the switching is disconnected. The plough structure 3 is stressed into coupling to the limit switch with two forcing means, in this exemplary implementation with spring means, namely by means of first springs 15 stressed between the suspension part 2 and the first element 4 and by means of second springs 16 stressed between the first element 4 and the second element 5. First adjusting means 17 (e. g. screws) for adjusting the prestress of the first springs 15, are arranged to cooperate with the first springs '15, and second adjusting means 18 (e.g. screws) for adjusting the prestress of the second springs 16, are arranged to cooperate with the second springs 16. Moreover, a first stop arrangement 19, against which the plough structure 3 is forced, is arranged in the vicinity of the first linking point (links 7), and a second stop arrangement 20, against which the second plough structure 5 is forced, is arranged in the vicinity of the second linking point (links 10), and by said second stop arrangement the plough element 5 is prevented from turning in relation to the second linking point 10 to the same direction as the entire plough structure 3 in relation to the first linking point 7.

The above-described plough structure 3 is such that when an obstacle in the crane's 1 path in the direction of motion, in front of the plough structure 3, mainly hits the area between the first and the se.dond linking point 7, 10 of the plough structure and slightly above the second linking point 10, i.e. an area B, or when the obstacle between the plough structure 3 and the crane 1 hits below the second linking point 10 (see Figure 4), the coupling part 14 of the plough structure 3 is disconnected from the lim it g-witch 13 against the force of the second springs 16, and only the second element 5 turns in relation to the second linking point 10, and when, in the crane's 1 path in front of the plough structure 3, the obstacle mainly hits below the second linking point 10 or the area of the second linking point ( i.e. also to some extent above the second linking point), that is, an area A, the coupling part 14 is disconnected from the limit switch 13 against the force of the first springs 15, and the entire plough structure 3 turns in relation to the first linking point 7, but in the opposite direction with the second element 5 in relation to the second linking point 10. This is illustrated in Figures 3 and 4.

Figure 3 illustrates a normal situation, in which for instance, a person (not shown) in front of the crane 1 on the ship deck produces a force F1 in an area A, and as a consequence, the safety arresting device operates on the basis of turning at the first linking point 7. The force of the springs 15 that re- sists the turning of the plough structure 3 is adjusted with the adjusting means 17 such that it is neither excessively weak, whereby the tripping might occur by itself while the crane is run, nor excessively strong, so that the crane 1 would cause damage to the person or some other obstacle ahead. In a situa- tion where a person with his head towards the crane 1 is lying on the deck, the safety arresting device is hit right in the lower edge, whereby the force that trips the operation of the safety arresting device is very weak.

Figure 4 illustrates a situation in which, for instance, on or between the hatches in front of the crane 1, there is a person or some other obstacle which produces a force F2 in an area B, as a consequence of which the safety arresting device operates on the basis of turning at the second linking point 10. In this case, only the second element 5 turns, since the stress of the springs 16 is adjusted by the adjusting devices 18 in such a way that the force F2 exerted in the area B is not sufficient to turn the entire plough structure 3 at the first linking point 7. A typical situation in accordance with Figure 4, which trips the safety arresting device is, that a person between the hatches reaches out towards the crane and his hand is trapped between the hatches and the safety arresting device. The hitting point is in the upper part of the safety ar resting device, and consequently the tripping force is very we ' 6k. The safety ar- resting device also operates by turning in relation to the second linking point 10, when an obstacle between the plough structure 3 and the crane 1 hits below the second linking point 10 (for instance, when the crane 1 is backed) with a sufficient force F3.

The limit switch 13 is preferably an inductive switch which has a signal on when it is coupled to the plough structure 3, and which operates immediately when the signal is broken off. If something goes wrong with the switch 13 (a wire breaks, for instance) the stopping operation of the crane trips immediately also in this case. By this arrangement, the safety arresting device is made very reliable and safe, for the crane does not move, if the switch 13 is broken.

Since the safety arresting device also operates in two directions the second plough element 5), its breakage is prevented.

Figure 5 illustrates one alternative implementation of the safety arresting device of the invention. Apart from the first forcing means 115 and ad- justing means related thereto, this solution is otherwise substantially similar to the construction illustrated in Figures 1 to 4. In this solution, an arm 21 is ar- 6 ranged to the first plough element 4, on that side of the link 7 which is opposite to the limit switch 13, and a counterweight 115 (a mass m), whose position along said arm is adjustable and lockable to place and which acts as the first forcing means, is mounted onto said arm. The quantity of the forcing power is simply adjusted by means of the counterweight position. This arrangement may locate on the opposite side of both links or just one link 7. Naturally, one option is one counterweight that is arranged in the middle of the beams 6 in the above-described manner in relation to the links 7.

The above specification of the invention is intended to illustrate the 10 basic idea of the invention. However, a person skilled in the art may implement its details in a variety of alternative ways within the scope of the appended claims. For instance, the forcing means can be implemented in a plurality of alternative ways, also other than those described in the above, and the same safety arresting device may simultaneously employ a combination of various forcing means. Moreover, it is to be noted in this connection that, in the spring arrangements 15, 16 described above in Figures 11o 4, it is possible to use only one spring or spring arrangement having effect on the linking point 7, and one spring or spring arrangement having effect on the linking point 10. The central idea of the invention is, however, the addition of thb second linking point 10 and its implementation, not the other details that can be implemented in a variety of ways.

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Claims

1. A safety arresting device of a crane (1) for stopping the crane by the effect of an obstacle in the crane's path, the safety arresting device comprising a plough structure (3) linked (7) in its upper part to the crane, in the front andlor rear of said crane, the plough structure being forced into switching, by means of forcing means (15; 115), to a limit switch (13) that allows or prevents the motion of the crane, whereby in a normal situation and said switching being implemented, it is possible for the crane to move, but when an obstacle in the path diverts the plough structure (3) against the force of the forcing means (15;115) off the said switching, the crane is prevented from moving, c h a r a c t e r i z e d in that the plough structure (3) has a second linking point (10) the plough structure has a second linking point (10) located below the above-mentioned linking point (7), and second forcing means (16) by means of which the plough structure is also forced into switching to said limit switch (13), and against whose force the limit switch is disconnected from the switching that allows the crane (1) to move, when an obstacle that is in the crane's path in the direction of motion, in front of the plough structure, mainly hits between the first and the second linking point (7,10) and slightly above the second linking point (10), or when an obstacle between the plough structure and the crane hits below the second linking point (10), on the other hand, said limit switch being arranged to be disconnected against the first forcing means (15; 115) from the switching that allows the crane to move, when an obstacle that is in the crane's path in the direction of motion in front of the plough structure mainly hits below the second linking point (10) of the plough structure or within the area of the second linking point, whereby turning in relation to the first linking point (7) is opposite to turning in relation to the second linking point (10).

2. A safety arresting device as claimed in claim 1, c h a r a c lt e r i z e d in that the plough structure (3) consists of two interlinked elements (4, 5), of which a first element (4) is linked to the first and second linking point (7, 10) and a second element (5) to the second linking point (10), whereby the part that comes into contact with the obstacle is in whole the second element (5), and whereby the entire plough structure (5) revolves about the first linking point (7) and only the second element (5) of the plough structure revolves about the second linking point (10).

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3. A safety arresting device as claimed in claim 1 or 2, c h a r a c t e r i z e d in that at least one of said forcing means (15, 16) are spring means.

4. A safety arresting device as claimed in claim 1 or 2, c h a r a c - t e r i z e d in that at least one of said forcing means (115) are counterweight means.