System for the lubrification of the cutter of pneumatic-operated chain saw

Abstract: The lubrication system is applied to a pneumatic-operated chain saw. A pneumatic engine (8) is secured to a casing (1) containing mechanical means for driving a gauge teeth chain (3), and a fore wing (la) of the casing (1) carries, fastened thereto, a blade carrying arm (2) for supporting and guiding the chain (3). Two handles (9,10) fastened to the casing makes it possible to use the saw. A reservoir (11), containing lubrication liquid, is connected to the casing (1) in such a manner that one its part (lla), featuring a hole (21), rests against the frame (18) of the pneumatic engine (8), featuring a corresponding hole (28). The two holes are joined by a pipe (12), which opens in an air zone inside the reservoir (11). A duct (13) extends from the reservoir (11) up to a point where the chain (3) passes, so that, due to the pressure of the air entering the reservoir (11), the lubrication fluid is sprayed toward the chain (3).

Description: The present invention relates to a saw operated by a pneumatic engine. Saws of this kind usually include a casing, which contains the engine activating the cutting element. An arm extends from the front part of the casing and a cutting element is set to turn around the arm. The cutting element is typically formed by a closed-loop chain, whose links have gauge teeth. Two handles for picking up and work control of the chain saw, are made integral to the rear part and to one side of the casing. One of the problems in the chain saw design derives from the necessity for lubrication of the cutting chain, which, during the saw operation, runs following the fore arm profile and introducing its suitable appendices in a peripheral groove made in this arm. Once, lubrication operation were made by periodically interrupting the cutting operation and manually applying the lubricant fluid to the chain. It is obvious that this system is not convenient, because it is necessary to interrupt longer cutting operations to add new lubricant fluid, that gets rapidly used up. According to one solution of the problem, a lubricant reservoir is situated inside the side handle and equipped with channels directed toward the chain. The lubricant is let out in a controlled way from the reservoir by overpressure formed thereinside by means of a sized pipe connected with the pneumatic engine discharge. In this case, the disadvantages derive from big dimensions of the handle, which could be offset only by providing a reservoir of insufficient capacity, and from the possibility of removing the handle only when the reservoir is empty, or only with particular precautions, so as to avoid the risk of undesired reversal of lubricant fluid. The Patent Application BO92U 000079 filed on 17.04.1992 discloses a chain saw in which the problem is solved by applying a technical solution used for internal combustion engine operated saw. There, the space inside the casing is big enough to house also a lubricant reservoir. A further example of a prior art device utilising an internal combustion engine for chain saw lubrication is known from US-A-4,882,555. The pneumatic chain saws are usually used for works requiring extremely reduced dimensions and weight, together with high handiness, which results in very limited internal space inside the casing. The technical solution disclosed in the Patent Application No. BO92U 000079 makes it possible to mount a reservoir inside the frame also in these cases. The reservoir must be shaped following the casing external shape and is housed thereinside where it is fixed by removable fastening, e.g. with suitable screws. The lubricant fluid is taken from the reservoir and applied by a pump fastened to the reservoir side. The pump outlet side is directed toward the external edge of the blade carrying arm, so that the lubricant taken from the reservoir is directed toward the arm. The pump is operated by an arm, which extends up to the point corresponding to the lateral handle and which is provided, in this area, with a push-button. The user can act on the push-button without interrupting the cutting operation. The object of the present invention is to provide a lubrication system for pneumatic-operated chain saws, as described previously, which applies lubricant in a completely automatic way, without distracting the user and without interrupting the cutting operation. Another object of the invention is to provide a solution, which is cheap, simple to construct and which does not condition functionally or dimensionally any part of the saw, except the casing. The suggested system is compact and practical and does not require any periodical activation intervention by the user. Obviously, it will be necessary to fill up the lubricant reservoir, but this operation can be performed in any moment without disassembling of any part of the chain saw. The simplicity of the system influences positively also its assembly speed, its cheapness and especially its operation reliability, since it does not include any active mechanical elements, like pumps or similar, which are expensive, fault-prone and require maintenance operations. The characteristics of the invention will become apparent from the following description with specific reference to the enclosed drawings, in which: Fig. 1 is a lateral schematic view of a pneumatic-operated chain saw in its basic form; Fig. 2 is an enlarged sectional view of a particular of the chain saw of Fig. 1. With reference to the above described figures, the lubrication system for the cutting element, being the subject of the present invention, is designed for a pneumatic-operated chain saw formed by a casing, that supports a pneumatic engine and contains mechanical driving means. A blade carrying arm 2 and two handles 9,10 are fastened to the casing. A reservoir 11 is provided for the lubricant liquid. In particular, the blade carrying arm 2 is removably fastened to a fore wing 1a of the casing 1, so as to support and guide the cutting element 3,4, formed by a close-loop chain 3, whose links 4 are equipped with appendices turned toward inside of the chain loop. These appendices are introduced into a peripheral groove made along the external edge of the blade carrying arm 2. A terminal part of the loop formed by the chain 3 is trained around a pinion keyed on the outlet shaft of the pneumatic engine 8, so that the chain 3 is driven into rotation when the engine is operated. According to known techniques, the blade carrying arm 2 is fastened by screws, that are not shown, which pass through a slot 5, made in the wing 1a, and engage with a longitudinal notch 6 made in the region of an end of the arm 2. The slot 5 allows longitudinal movements of the arm 2 in order to adjust the chain 3 tension and to allow its substitution, while the arm oscillation is prevented by a peg 7, extending from the wing 1a and inserted in the notch 6. According to the invention, the reservoir 11 is connected with the casing 1 in such a way that a part 11a of its external surface rests against the frame 18 of the pneumatic engine 8. According to a first embodiment, the reservoir 11 is manufactured as one body with the casing 1 and is situated above the frame 18. According to another embodiment, the reservoir 11 is removably fastened to the casing by locking elements, e.g. screws, not shown in the drawings. In both cases, the reservoir 11 has a through hole 21 made in its part 11a resting against the frame 18. The frame 18 features a corresponding hole 28 crossing the area 18a, against which the reservoir 11 rests. Thus the two holes coincide. The compressed air used for operation of the pneumatic engine is normally discharged through suitable openings made in the frame 18. The hole 28 made in the area 18a of the frame, opens in the air discharge collector, which leads to the above mentioned openings. As a result, a part of the discharged air goes out through the hole 28, which can be, although not necessarily, sized, and returns inside the reservoir 11, creating there a light overpressure. There are provided check means 12 which allow only discharge air to pass from the frame 18 to the reservoir 11, thus preventing the lubricant liquid from flowing in the opposite direction. Finally, a duct 13 extends from the reservoir 11 up to a point, where the chain 3 passes, so that, due to the pressure of the air entering the reservoir 11, the lubricator is pushed along the duct 13 until it is spread on the cutting element 3, 4. According to a further embodiment of the invention, with reference to the fig. 2, the duct 13 engages, by screwing, with a through hole 17 of the wing 1a of the casing 1, so as to be connected with a hole 2a of the arm 2 communicating with the already mentioned peripheral grove guiding the chain 3. The duct 13 can be connected to the wing 1a by means of a screw connector 14, of known type, that has a screw 19 set in its external part for regulating the flow that passes through the connector. Therefore, it is possible to adjust the flow of the lubricant liquid to the chain 3 by acting on the regulation screw 19. An oblong recess 15 is provided on the surface of the wing 1a against which the arm 2 strikes, in the region of the through hole 17, in order to allow the connection between this hole 17 and the hole 2a of the blade carrying arm 2, independently from their reciprocal position within the interval of the chain 3 tension adjustment. Therefore, the lubricant flows through the duct 13 into the cavity 15 and reaches the hole 2a, even if this hole is displaced with respect to the hole 17. For improving the system operation, the check means 12 for the passage of only discharge air from the frame 18 to the reservoir 11, include a pipe 12 screwed into the holes 28,21 and opening in an air zone inside the reservoir 11. Otherwise, or additionally, a one-way valve can be provided, which is not shown in the drawings.

Claims: System for lubrication of the cutting element (3,4) of a pneumatic-operated chain saw of the type including: a casing (1); a pneumatic engine (8) fastened to the casing (1) for operating said cutting element (3,4); driving means, housed in said casing (1) and connected to said engine (8) for driving said cutting element; a blade carrying arm (2) removably fastened to a wing (1a) of said casing (1) for supporting and guiding said cutting element (3,4), and a reservoir (11) adapted to contain lubricant liquid; said system characterised in that said reservoir (11) is connected with said casing (1) in such a way that a part (11a) of its external surface rests against the frame (18) of said pneumatic engine (8), in that the reservoir (11) features a first through-hole (21) made in its part (11a) resting against the frame (18), in that said frame (18) features a second through-hole (28) in the area (18a), where said reservoir (11) rests, so that said reservoir first through-hole (21) and said frame second through-hole (28) coincide with each other, in that there are provided check means (12) which allow only the discharge air to pass from the frame (18) to the reservoir (11) and prevent in use, the lubricant liquid from flowing in the opposite direction, and in that a duct (13) extends from the reservoir (11) up to a point, where said cutting element (3,4) passes, so that, due to the pressure of the air moving from the engine frame (18) inside the reservoir (11), the lubricant liquid is pushed along said duct (13) until it is spread on said cutting element (3,4). System, according to claim 1, characterised in that said duct (13) originates from the reservoir (11) and is connected, in screw engagement, with a through hole (17) made in said wing (1a) of said casing (1), against which said blade carrying arm (2) strikes, so that said duct (13) is connected with a hole (2a) of the arm (2) communicating with a peripheral grove guiding said cutting element (3,4). System, according to claim 2, characterised in that the duct (13) is connected to the wing (1a) by means of a screw connector (14), that has a screw (19) set in its external part for adjusting the flow that passes through the connector. System, according to claim 2, characterised in that an oblong recess (15) is made in the surface of the wing (1a) of said casing (1) against which the blade carrying arm (2) abuts, in the region of said through hole (17), in order to allow the connection between this hole (17) and the hole (2a) of the blade carrying arm (2), independently from their reciprocal position, within the interval of the cutting element (3,4) tension adjustment. System, according to claim 1, characterised in that said check means (12) for the passage of only discharge air from the frame (18) to the reservoir (11), include a pipe (12) screwed into said holes (28,21) made in said reservoir (11) and in said frame (18) and opening in an air zone inside the reservoir (11). System, according to claim 1, characterised in that said check means (12) for the passage of only discharge air from the frame (18) to the reservoir (11), include a one-way valve. System, according to claim 1, characterised in that said reservoir (11) is integral with said casing (1) and is situated over the frame of said pneumatic engine (8). System, according to claim 1, characterised in that said reservoir (11) is removably connected with said casing (1) by locking means and is situated over the frame of said pneumatic engine (8). System, according to claim 1, characterised in that said cutting element (3,4) is formed by close-loop chain (3), whose links (4) are equipped with gauge teeth.

Inventors: VITTORIO FERRETTI PIO, VITTORIO, FERRETTI PIO
Applicants: CAMPAGNOLA S R L, CAMPAGNOLA S.R.L.
Application year: 1997
Main classification: B27B17
IPC codes: F16N7, B27B17