Suspension bar for helicopter for mounting working equipment

(54) (56) (57)

PATENT INVENTOR INVENTOR'S OFFICE DESCRIPTION OF PUBLICATIONS: SUMMARY:

Dental Village SE

Helitool Europe AB, Box 48 830

Stefan Öwre, Östersund SE, Bengt Åsberg, Örebro SE Kransell & Wennborg AB

Helicopter suspension bar

Device at a bar which is intended to be suspended under a helicopter (1) or the like for carrying an equipment, e.g. a sawing equipment for tree branching, to be operated by the helicopter. The rod is thus designed so that if its lower end is subjected to an upward compressive force this force is dissipated or substantially weakened before it reaches the upper end of the rod (5) connected to the helicopter (1). This avoids any upward force of harmful size hitting the helicopter as a result of this suddenly dropping a few meters.

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519 040

Field of the Invention

The present invention relates to a device at a bar which is intended to be suspended under a helicopter or the like for carrying an equipment, e.g. a sawing equipment for tree branching, to be operated by the helicopter.

Background of the Invention

Helicopters are used today for more and more tasks that previously could only be performed from the ground. One such task is to clear power lines, ie sawing of tree branches and the equivalent extending too close to a power line. This is done by means of a sawing equipment mounted on a rod hanging from the helicopter, which carries a number of saw blades and a motor for driving the blades as well as the necessary transmission means. The part of the bar carrying the saw blades can, for example, have a length of 5 m and be connected to a supporting rod of about 15 m attached to the helicopter.

Equipment of this type is described in US Patent Nos. 4554781 and 4815263. To enable the helicopter to put down the sawing equipment on, for example, trestles on the ground, the rods are provided with joints. The bar according to US Patent No. 4554781 is additionally constructed with an angled portion to avoid the bar being obstructed by the helicopter during closure, see Fig. 2.

In use, however, the rod hangs straight below the helicopter so that the articulation points are located substantially along a straight line between the rod supporting the saw blades and the attachment point of the helicopter.

This also applies to the device of the other American

519 040 patent 4815263.

A safety problem with known devices of this kind is that serious accidents can occur as a result of the rod hanging from the helicopter being pushed upwards and inwards through the helicopter casing. This can be eg happens on the helicopter for any reason, e.g. a temporary engine failure, rapidly descending a few meters in height, so that the saw blades supporting the bar hit the ground or other solid ground. The same effect can occur if the saw blades get stuck when pressed downwards through a branch mill.

The object of the invention

The main object of the present invention is to provide a device for rods for mounting suspended working equipment on helicopters, which eliminates or substantially reduces the risk of accidents caused by pushing the upper end of the suspension bar up towards the helicopter.

The basis of the invention is the insight that this can be achieved by performing the rod connected to the helicopter in such a way that compressive forces affecting the lower end of the rod cannot be conveyed to the upper end of the rod connected to the helicopter.

The particular characteristic of a device of the kind specified in the first paragraph is that the rod is designed so that if its lower end is subjected to an upward compressive force this force is dissipated or weakened substantially before reaching the upper end of the rod connected to the helicopter, so that any upward force of harmful size does not hit the helicopter.

A temporary engine malfunction or other that can cause the helicopter to suddenly drop a few meters, so that

519 The 040 rod bumps against the ground, thereby not resulting in the rod being pushed upwards and into the helicopter.

One way to achieve this result is to perform the rod with a hinged knee, which in the working position is adjacent to a line extending between the lower and upper ends of the rod, connected to the work equipment and the helicopter, respectively. Such an embodiment of the bar means that a compressive force acting on the lower end of the bar will result in the bar being pivoted around the knee joint, which is thereby pressed sideways without imparting any significant force to the overlying portion of the bar.

According to a particularly preferred embodiment, the rod connected to the helicopter is formed in the form of at least two telescopically movable tubes relative to each other. In the working position, the pipes are fully extended and rotatable relative to each other. However, the tubes may be pushed together by exerting a force on the end of the lower tube. Thus, this force will not be conveyed to the attachment in the helicopter.

Further features of the invention are set forth in the following claims.

The invention will be described in more detail below with reference to the embodiments shown by way of example in the accompanying drawings.

Brief description of the drawings

Fig. 1 shows a helicopter with a sawing equipment for clearing power lines and the like.

Fig. 2 shows the mounting device in the helicopter on a larger scale.

Fig. 3 shows an embodiment of the helicopter connected

519 The 040 bar in the pushed state.

Fig. 4 shows the bar of Fig. 3 in fully extended condition.

Fig. 5 shows an alternative embodiment of the rod connected to the helicopter.

Figs. 6 and 7 show the bar of Fig. 5 in a position when its lower end is subjected to an upward compressive force.

Fig. 8 shows the bar of Fig. 5 in the folded state.

Detailed description of preferred embodiments

Fig. 1 shows a helicopter 1 with a device for clearing power lines and the like. This equipment comprises a number of saw blades 3 mounted along a boom 2, which are driven from an internal combustion engine 4 via transmission means arranged in the boom. The sawing equipment can be of conventional type and is completely rigid and is connected to a rod 5 suspended in the helicopter 1 via a link 6. In the embodiment shown, the bar 5 is formed in the form of two relatively telescoping telescopic pipes 7 and 8, respectively, which can be made of aluminum and have a total length of about 15 m. The upper, in this case the inner tube 7, is connected to an upper mounting plate 9 with a loop or hook 10 for mounting on the helicopter, see Fig. 3.

As can be seen more clearly in Fig. 2, plate 10 is provided with two torque arms 11 connected to the plate, the other ends of which are connected to both helicopters of the helicopter via each ball joint 30. The arms 11 take up rotational movements of the plate 9 and the pipe 7, which must be rotatable relative to the helicopter.

519 040

<img file="SE519040C2_D0003.tif" />

In Fig. 3, the bar 5 is shown on a larger scale, with parts of the outer tube 8 and the inner tube 7 being cut away to show the construction more clearly. The bar 5 is intended to be suspended in the helicopter via the mounting loop 10, while the sawing equipment is intended to be pivotally attached to the bar 5 by means of a guide shaft 6 at its lower end. Between link 5 and the helicopter, a link 31 may be provided, see FIG.

2.

The inner tube 7 is rotatably connected to the mounting plate 9, which in turn is rotatably coupled to the helicopter via the torque arms 11. The pivot shaft 6 is arranged in a lower coupling part 12 in the outer tube 8 which protrudes through the lower end of the tube 8. In the upper part of the outer tube a fiber sleeve 13 is fixed, which at the displacement of the outer tube 8 relative to the inner tube 7 slides against the outer surface of the tube 7. 14 and 15 denote two steel sleeves arranged around the inner tube 7 which, in the fully extended position of the outer tube 8, see Fig. 4, enter machined seats, not shown, on the inner surface of the fiber sleeve 13. In this position, the inner and outer tubes 7, 8 are kept accurately controlled relative to each other without mutual glitch. 16 denotes a slotted plastic ring which slides against the inside of the outer tube upon extraction thereof relative to the inner tube 7.

The lower edge portion of the fiber sleeve 13 is formed with a number, in this case 4, recesses 17 with wedge-shaped side surfaces and a rounded top. The steel sleeve 15 is provided with at least one and preferably two engagement means 18 projecting towards the outer tube. Upon extraction of the outer tube 8, the recesses 17 will have the function of seats which receive the wedge-shaped projections 18, see Fig. 4, and stop the extraction of the outer tube 8. The fiber sleeve 13 and the outer tube 8 are thereby irreversibly locked to the inner tube 7 and thus also to the plate 9.

519 040

The use of wedge-shaped or triangular seats 17 and projections 18 facilitates the telescopic tubes 8 and 7 being pushed together after completion of the working operation. Otherwise, this can be difficult if the helicopter has been slightly rotated, so that there is a rotational force between the outer tube and the inner tube, which lock them relative to each other and make an axial displacement of the outer tube 8 relative to the inner tube 7 difficult. With the wedge-shaped engagement surfaces of the seat 17 and the cooperating projection 18, such a rotational force provides a component in the axial direction which facilitates the telescopic tube collapse.

As shown in Fig. 4, the suspension loop 10 is connected to a piston rod 19 running through the mounting plate 9 which is connected to a piston 20 running in a housing 21. The piston is pressed against its lower end position by means of a compression spring.

22nd The housing 21 is suitably filled with oil, the piston 20 being provided with overflow means which allows the oil with a certain resistance to pass from the chamber above the piston 20 to a chamber below the piston 20 as it is drawn upwards due to an instantaneous large pulling force in the loop. 10. This results in a damping function, the purpose of which will be described in more detail below.

The device described above is used as follows.

The starting position is that the sawing equipment 2, 3, 4 and the telescopic rod 5 attached to this articulator are on the ground. A lifting hook 32 present on the helicopter 1 is thereby coupled pivotally to the lifting eye 10, e.g. via a link 31, after which the torque bars 11 are attached to the helicopter's landing gear, via the ball joints 30, so that the telescopic rod 5 can only swing in a forward and backward direction relative to the helicopter 1. When the helicopter then lifts, the telescope tube 5 will be pivoted upward relative to the ground 2 which is left on the ground with the saw blades 3. When utilizing previously known

519 040 fixed length rods, in order to avoid the sawing equipment being dragged along the ground, the helicopter must rise in such a way that the lifting eye 10 describes a circular arc with the center at the pivot point 6. In the past, the pilot has usually strived to provide a small pressure against the suspension rod. However, it is difficult to accurately weigh this pressure, so there is a risk that the bar will be broken by the load.

With the use of a telescopic rod 5, the pilot need not produce such pressure and any deviation from the circular arcuate motion of the suspension loop 10 will be compensated by pulling or pushing the tubes 7 and 8 relative to each other. It is therefore advisable that the lifting operation starts with the pipe 8 to half the length of the extension.

When the helicopter has reached such a height that the sawing equipment is also lifted from the ground, the weight thereof will pull down the outer tube 8 to its lower end, shown in Fig. 4. The outer tube, which is rotatably connected to the boom 2, which supports the saw blades 3, is then automatically locked in the desired rotational position relative to the inner tube 7, so that the blades 3 are located on the correct side of the boom 2 for the intended cutting direction. This means that the blades 3 should be facing, ie located between the boom 2 and the trunk of the tree whose branches are to be cut.

As a result of the rod 5 being telescoping, the outer tube 8 will be pushed up on the inner tube 7 upon the occurrence of a compressive force on the lower end of the saw equipment. This can happen if the helicopter, e.g. due to temporary engine failure, drops to the ground so that the sawing equipment strikes the ground. A similar risk can also arise if the saw blades 3 become trapped in the branch on a tree when the helicopter suddenly drops. With the described device, this will only result in the outer tube being pushed up correspondingly on the inner tube. The risk of the helicopter and its crew being damaged as a result of the suspension tube being pushed into the helicopter in such an event is thus eliminated or greatly reduced.

Since the saw blades are to be on the right side of the beam 2 relative to the tree trunk, there is a need to be able to turn the saw equipment 180 ° relative to the suspension bar 5. For example, this need arises when clearing in strong sloping terrain, since the helicopter can not cut in the direction down a slope with severe slope, as the tail portion thereby risks coming into contact with the ground. In the case of previous equipment, it has been forced to use extension rods to hang the saw equipment at greater distances under the helicopter. Alternatively, the saw equipment must be laid down on the ground and decoupled from the helicopter in order to be turned 180⁰ and again suspended in the helicopter.

Using the above-described device according to the invention, for such a rotation, the helicopter driver only needs to lower the saw equipment so that the lower part abuts the ground and then lower the helicopter further at least about 7 cm so that the triangular engaging means 18 is released from associated seat 17. The driver can then turn the helicopter 180 ° and lift the equipment from the ground. In this case, the engaging means 18 will cooperate with a seat 17 located on the opposite side of the fiber sleeve 13 and again lock the outer tube 8 in a rotating direction relative to the inner tube 7 in the new position. Depending on the number of seats 17 and / or engaging means 18, the desired number of adjustment positions between the outer and inner tubes 8, 7 can be obtained.

519 040

<img file="SE519040C2_D0004.tif" />

The above-described damping device comprising the spring 22, the piston 20 and the housing 21 has the purpose that if the telescopic rod 5 is pulled out to reduce the stresses on both the suspension hook 32 in the helicopter 1 as well as on the saw equipment. Such a rapid pull-out of the suspension rod can occur, for example, if the rod is involuntarily pushed together when in contact with a heavy branch on a tree and then released again.

In Fig. 5 an alternative embodiment of the suspension bar 5 is shown. This consists of two pivotally connected rods 23 and 24, of which the rod 23 is intended to be pivotally attached to the helicopter and the rod 24 to be pivotally attached to the boom 2 carrying the saw blades 3. At its opposite ends, each rod is provided with an angular portion 25, which portions at its outer ends are pivotally connected to each other via a pivot pin 26. In the working position, the weight of the sawing equipment provides a pulling force in the rods 23 and 24, holding them in the position shown in Fig. 5, the angular portion 25 of the lower rod resting on a stop heel 33 projecting from the angular portion of the upper rod.

If the helicopter suddenly drops so that the sawing equipment hits the ground and a compressive force arises on the lower end of the rod 24, see Figs. 6 and 7, the rods 23 and 24 will be pivoted relative to each other around the joint shaft 26, since it is located side by side. a line connecting the outer ends of the rods 23 and 24, see Fig. 5. Thus, the resulting compressive force on the lower end of the rod 24 will result in the folding of the complete rod 23, 24 around the pivot shaft 26, whereby no harmful compressive force will be conveyed to the suspension hook 32 of the helicopter.

The bar shown in Figs. 5-7 can also be folded together

519 040 or half of its original length, as illustrated in Fig. 8.

The invention has been described above with reference to the embodiments shown in the accompanying drawings, by way of example. These, however, as those skilled in the art will readily recognize, may be varied in several respects within the scope of the claims while retaining the desired function of eliminating the risk of damaging compressive forces on the helicopter due to the fact that a working equipment e.g. comes into contact with the ground. For example, the telescopic rod shown can be varied so that the outer tube is connected to the mounting plate and the inner tube to the sawing equipment. Furthermore, the stop means and corresponding seats can also be changed.

519 040

II