TECHNICAL HELD

The present invention relates to a method, in the felling of trees, of preventing or inhibiting decay in a remaining tree stump, the tree being sawn from the tree stump using a chain saw with a guide bar, and the remaining tree stump being sprayed with a decay-preventing or decay- inhibiting agent.

The present invention also relates to a device, in the felling of trees, for preventing or inhibiting decay in a remaining tree stump, and comprises a chain saw with a guide bar, and diffuser means for spraying the tree stump with a decay-preventing or decay-mhibiting agent.

BACKGROUND ART

In felling trees, the remaining tree stumps are infected by spores from conk (bracket or shelf fungus), which is a decay fungus capable of being spread to healthy and growing trees so that these are damaged or killed. The infection by fungus spores takes place through the air as soon as temperatures are sufficiently elevated, which implies that all forestry clearance during the summer months is risky.

Attempts have previously been made using various fungicides etc., to spray the remaining tree stumps in order hereby to inhibit or wholly prevent infection and consequential spread of the decay. In such instance, two different types of preparations have been employed, on the one hand chemical fungicides and, on the other hand, means for disseminating spores from other types of fungus which compete with and prevent the occurrence of the harmful decay fungus.

Equipment for disseminating the above-mentioned liquid fungicides have previously comprised a specially manufactured guide bar for the chain saw which is employed in the clearance felling. This guide bar features interior

ducts with apertures via which the fungicide is sprayed out against the tree stump in connection with the felling of the tree.

Since guide bars may more ore less be considered as expendable items, the prior art technology has proved to be extremely expensive and impractical. In addition, the consumption of fungicide has also been excessively high.

PROBLEM STRUCTURE

The present invention has for its object to devise the method intimated by way of introduction such that the drawbacks inherent in prior art methods are obviated. In particular, the present invention has for its object to realise a method in which combating decay and rot may be effected rapidly and conveniently, at the same time as forestry clearance takes place, and with extremely slight consumption of fungicides. The present invention further has for its object to realise a method which does not complicate the replacement of guide bars, or make this an expensive operation.

The present invention yet further has for its object to design the device intimated by way of introduction such that it obviates the problems inherent in prior art technology. In particular, the present invention has for its object to realise a device which is simple and economical in purchase and use, which does not prevent the replacement of guide bars and which eliminates the need for specially manufactured guide bars. Finally, the present invention further has for its object to realise a device which reduces consumption of fungicides.

SOLUTION

The objects forming the basis of the present invention will be attained in respect of the method if this is characterized in that at least one jet of fungicide is sprayed approximately in the longitudinal direction of the guide bar towards its tip or head, and on the side thereof facing towards the tree stump.

Further advantages will be attained in respect of the method, if this is also given one or more of the characterizing features as set forth in appended Claims 2 to 7.

The objects forming the basis of the present invention will be attained in respect of the device, if this is characterized in that the diffuser means comprise at least one nozzle in the region of the anchorage of the guide bar, this nozzle being disposed for emitting at least one jet of the decay- preventing or inhibiting agent substantially in the longitudinal direction of the guide bar, towards its tip or head, and on the side of the guide bar facing towards the tree stump.

Further advantages will be attained in respect of the device, if this is also given one or more of the characterizing features as set forth in appended Claims 9 to 14.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detail hereinbelow, with particular reference to the accompanying Drawings. In the accompanying Drawings:

Fig. 1 is a schematic vertical side elevation of a part of a guide bar and its anchorage; and

Fig.2 shows the device of Fig. 1 seen from beneath.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the Drawings, in Fig. 1, which schematically illustrates in vertical side elevation a part of a cutting unit, reference numeral 1 relates to a lower anchorage and reference numeral 2 an upper anchorage for a guide bar 3. Further, reference numeral 4 relates to a drive motor which is preferably hydraulic and which, via a schematically illustrated sprocket 5, drives a saw chain (not shown in Fig. 1).

In Fig. 2, a saw chain 6 is intimated along opposing edges of the guide bar 3, the chain having a cutting part 7 and a return part 8. According to the invention, the guide bar 3 and chain 6 may be of fully conventional type, for which reason no mechanical intervention or special adaptation need be made to these components.

According to the invention, at least one jet 9 is emitted substantially in the longitudinal direction of the guide bar out towards its tip or head. The point of impingement 10 between the jet 9 and the guide bar 3 is located a slight distance from the anchorage 1 and 2 of the guide bar, in practice this distance possibly needing to be varied in dependence upon the thickness of the tree which is to be felled. As suitable distance from the anchorage 1 to the point of impingement 10, mention might be made of the order of magnitude of 8 to 10 cm, but both smaller and greater distances may be appropriate when thinner or thicker trees are to be felled.

According to the invention, the nozzle 11 which emits the jet of agent for inhibiting or preventing the spread of decay is suitably adjustable so that the distance between the nozzle 11 and the point of impingement 10 of the jet 9 on the guide bar 3 may be varied. One method of reahsing this is to vary the angle between the jet 9 and the longitudinal direction of the guide bar 3. Those angles which may come into consideration lie in the range of between 2 and 8°, but may suitably amount to approx. 5°. Another method of varying the above distance may reside in moving the discharge aperture of the nozzle 11 for the jet 9 closer to or further away from the guide bar 3.

Also depending on the thickness of the tree which is to be felled, different jet diameters may be needed. For achieving this object, the nozzle 11 may either be replaceable or adjustable so that the through-flow aperture lies in the size range of between 1.0 and 2.5 mm.

For supply of the decay-inhibiting or decay-preventing agent, a duct 12 is provided in the lower anchorage 1 of the guide bar 3, this duct optionally being provided with a connection 13 on the underside of the anchorage, but also optionally being provided with a connection 14 on the upper anchorage 2.

The device further includes a storage container or reservoir for the decay- inhibiting or decay-preventing agent, this reservoir being connected via a line to a pump arrangement which, via a discharge conduit, is in communication with one of the connections 13 and 14 on the anchorage of the guide bar 3. The pump arrangement is further in communication with a control unit which controls operation of the pump.

The control unit is designed in such a manner that a ready signal is emitted for initiating a work cycle in the pump arrangement as soon as the cutting unit with the chain 6 is started. In this instance, the control unit includes a delay circuit which, with optional delay after start of the cutting unit, starts the pump so that the jet is established along the lower planar side of the guide bar. The control unit further includes an adjustable time regulator for the time during which the pump is activated so that the jet is thereby emitted during a corresponding time interval. Furthermore, the control unit also suitably includes the possibility of regulating the discharge pressure from the pump arrangement so that this pressure may be set in the range of between 10 and 25 bar.

A typical work cycle for the above described device may have the following appearance. The cutting unit is brought into the proximity of the tree which is to be felled, whereafter the cutting function of the device is started. At the same time, the control unit receives a signal that cutting has been commenced and that the tilt function for felling the tree is activated. When the cutting operation commences, the above-mentioned delay time is activated, this suitably lying in the range of between 0.1 and 1.0 sec. When this interval has expired, the pump arrangement is activated so that the jet 9 of agent is emitted. The emission continues first as long as the cutting operation is activated and then, when this has been completed (and the saw chain 6 has thus stopped), diffusion of agent is continued for a certain time, suitably within the range of between 1 and 3 sec, at the same time as felling of the tree is completed.

It is appropriate if the nozzle 11 is placed a shorter distance to the cutting part 7 of the chain 6 than to the return part 8. In this instance, the ratio between that section of the guide bar 3 which, in the cutting direction, is

located ahead of the jet 9 and that section of the guide bar which is located behind the jet amounts to 1:2 or 1:5. The jet will therefore be emitted approximately parallel with the cutting part 7 of the chain 6 and at a relatively short distance (in practice often between 15 and 35 mm) therefrom.

It was disclosed in the foregoing that the nozzle 11 emits a single jet 9. In certain cases, an improvement of this function may be achieved if the nozzle is designed for emitting two or more jets so that these may thereby impinge on the planar side of the guide bar at different distances from the nozzle. It is also possible to cause such jets to run parallel with one another so that they impinge on the guide bar at approximately the same distance from the nozzle. Furthermore, several separate nozzles may be employed instead of a twin or multiple nozzle, these nozzles being of different diameters and through-flow areas and being individually adjustable or replaceable.

Further modifications may be made without departing from the spirit and scope of the appended Claims.