US2896746A - Automatic oiling device for chain saws - Google Patents

Description

limited St tes Patent Ofiice Patented July 28, 1959 Austin Gudmundsen, Inglewood, Calif., assignor to McCulloch Motors Corporation, Los Angeles, Calif., a corporation of Wisconsin Application November 23, 1956, Serial No. 624,091

Claims. (Cl. 184-15) This invention relates to an automatic lubricating system for use with two cycle engines and relates in particular to means for automatically oiling the saw chain and saw chain supporting bar of a chain saw de- Wn'ce powered by a crankcase scavenged two cycle engine of the type in which the lubricating oil is mixed with the fuel.

Chain saw devices of the type used for cutting timber require frequent application of lubricating oil to the saw blades chain supporting groove and to the chain. For this purpose a small oil tank with hand operated piston pump is provided on the chain saw device. If the chain saw operator forgets to operate the oil feeding pump, overheating, sticking, rapid wear and breakage of the saw chain may result.

It is an object of the present invention to provide an automatic oiling device which feeds small but effectively substantial quantities of oil residue from the crankcase of the engine to the saw chain and to the groove in which it travels.

It is an object of the invention to provide an oiling system which utilizes oil from the oil containing gaseons fuel mixture which moves through the engine crankcase to the fuel inlet port in the side wall of the engine cylinder.

It is an object of the invention to provide an oil accumulator disposed adjacent to or in the fuel passage which leads from the crankcase along a side of the engine cylinder to the fuel inlet port, this oil accumulator being characterized by its ability to absorb lubricating oil from the fuel mixture, and there being means for intermittently releasing oil from the oil accumulator into a duct which leads to the chain carrying groove in which the saw chain travels, thereby providing these parts with ample lubrication without it being necessary for the operator to work a lubricant pump.

It is an object of the invention to provide in a position along the path of flow of the fluid mixture within the crankcase of the internal combustion engine, an

oil collector comprising an oil absorbent structure hav-' ing capillaries extending from one face thereof to another face thereof. In this device the oil collector is arranged so that the one face of the oil collector is exposed to the fuel mixture and the other face thereof is in communication with the oil outlet passage having therein means for preventing reverse flow of fluids through the collector during the suction cycle in the engine crankcase. Therefore, oil accumulates in the collector during the suction and compression cycles within the crank case, and small quantities of the oil are discharged from the collector during the compression cycles within the crankcase.

Further objects and advantages of the invention may be brought out in the following part of the specification wherein many details are described for the purpose of competence of disclosure without, however, intending to limit the scope of the invention which is defined by the appended claims.

Referring to the accompanying drawings which are for illustrative purposes only:

Fig. 1 is a schematic elevational view showing an en gine powered chain saw employing the invention;

Fig. 2 is an enlarged fragmentary section showing one embodiment of the invention;

Fig. 3 is a fragmentary sectional view taken as indicated by the line 3-3 of Fig. 2; and

Fig. 4 is an enlarged fragmentary sectional view showing an alternative form of the invention.

Fig. 1 schematically shows a portable chain saw having an elongated flat blade 10 the periphery of which is provided with a groove along which a saw chain 11 travels. Power unit 12 is connected to the rear end of the bar 10 and includes a two cycle internal combustion engine 13 for supplying power to rotate a sprocket, not

shown, which drives the chain 11 so as to cause it to travel around the periphery of the blade 10.

As shown in Fig. 2, the engine 13 includes a cylinder 14, a crankcase 15 and a crank 16 which is connected by 'a connecting rod 17 with a piston 18 which reciprocates within the cylinder 14. The cylinder 14 has a portion 19 which extends into the crankcase 15 so that a fuel air passage 20 is formed along the side of the cylinder portion 19 for connecting the fuel air inlet 21 of the cylinder 14 with the crankcase space 22 in which the crank 16 revolves.

An oil accumulator 23 is disposed so that one face 24 is arranged along the fuel air passage 20 of the crankcase. The oil accumulator 23 comprises an approximately flat oil absorbent member or structure 25, the upper face 24 of which is arranged along the lower part of the passage 20 and along the path of flow of the oil containing gaseous fuel air mixture which is moving, as indicated by arrows 26 from the crankcase space 22 to the cylinder fuel inlet port 21.

The oil absorbent member 25 is characterized by having a multiplicity of small spaces in which oil may accumulate, these spaces being in the form of capillaries which connect the upper face 24 of the member 25 with the lower face 27 thereof, so that oil which enters the cellular or capillaceous oil collector member 25 may pass through the member 25 and be subsequently discharged through a check valve 38' associated with an outlet passage 28. Means 29 are provided through which oil leaving the outlet passage 28 is delivered to a duct 30 for carrying the oil to the groove of the saw bar 10 and to the chain to continuously maintain them in lubricated condition. a

The accumulator structure 23 is shown as comprising three plates 31, 32 and 33 which are bolted onto the crankcase 16 so as to cover an opening 34 in the lower wall of the crankcase opposite the inwardly projecting portion 19 of the cylinder 14. The oil collector 25 has a felt layer 35 arranged between an upper screen 36 and a lower screen 37. At least the upper screen 3-6 is flocked so that it will have high absorbent qualities. The middle plate 32 is disposed against the lower screen 37 and in its upper face has a shallow recess 38 which provides communication of the upper end of the outlet opening 28 with the lower face 27 of the oil collector 25. Means are provided for controlling the flow of oil from the collector 25 through the outlet opening 28. This control means responds to pressure within the crankcase 15 during the compression cycle therein. In the simple form disclosed, the flow controlling means comprises a reed valve 38' secured to the lower face of the plate 32 by rivets 39 and being posi-, tioned so that its free'end 40 covers the lower end ofthe outlet opening 28. The plate 33 covers. the reed outlet opening 28 to the duct 30.

The direction of rotation of the crank 16 is indicated by an arrow 42. As the crank moves downwardly from the position in which it is shown the piston 18 will be moved outwardly in the cylinder, and this movement of the piston. willact -to draw'thefuel mixture into the crankcase space 22, at a time when the piston 18 is com during the compression cycle, the pressure acting down wardly through the collector 25'will cause a small flow of oil outwardly through the outlet opening 28, depressing the free end 40 of'the reed valve 38' downwardly so that the oil will pass the reed valve and enter the passage 41. During the suction cycle within the crank case-space 22 there will be no flow of fluid upwardly for the reasonthat the reed valve 38 will return to its posi-' tion closing the outlet opening 28, thereby acting as a check valve to prevent upward flow of fluid from the outlet opening 28 and through the oil collector. Therefore, it is only the downwardly acting pressure .difierenti-al applied to the oil collector 25 during the compres sion cycle within the crankcase space 22 which can eifect movement of oil through the collector 25,-and since this movement of oil is in outward or downward direction, there results an intermittent feeding of oil past the valve 38 through the passage 41-to the duct 30 which leads to the parts which are to be lubricated. The oil feeding means 23 is placed in such relation to the rotation of the crank 16 and to the space 22 that small oil droplets in the fuel mixture are thrown downwardly and leftwardly so that they accumulate and flow downwardly along the lower crankcase wall or directly through themouth of the passage 20 to the oil collector 25.

In order to feed the oil quite rapidly and in spaced quantities or slugs through the duct 30, the invention also provides means, 'as shown in Fig. 4, for feeding small. quantities of gas-into the entrance of the oil de-- livery duct 30, it being understood that the invention may be practiced with or without this gas feeding means. This gas oil slug system can be accomplished in one of two ways. First, by properly proportioning the area-, and thickness of the oil absorbing pads with the size and stiffness of the outlet check valve, and size of associated passages, so that the pad is substantially purged of oil on each cycle which allows some gas to flow through the pad and check valve also. This results in a small quantity of oil followed bya larger slug of gas which acts an oil accumulator contiguous to said passage exposed to the oil containing, gaseous fuel mixture which flows through said passage, said oil. accumulator comprising an oil collector in which oil from the mixture accumulates; walls forming an outlet passage for conducting oil from said oil collector, said outlet passage being adapted to be connected to a duct for conveying oil to the chain of the chain saw device; fluid flow controlling means operating in said. passage to control the flow of oil from said oil collector; and means operating in response to periodic increases in gas pressure in said crankcase due to recipro cation of the piston of the engine to admit spacedquantities of gas into said duct to separate the oil flow therein into spaced quantities.

2. In an automatic chain oiling means for a chain saw device having a two cycle engine provided with a cylinder having a fuel inlet port in the side wall thereof and a fuel passage leading from the engine crankcase along the side of the. cylinder to. the fuel inlet'opening: :an oil collector. contiguous to said passage, "comprising an oil absorbentbody havinga face thereof exposed to the oil containing, gaseous fuelmixture in said passage;- walls forming an. outlet passage communicating with another face ofsaidiabsorbentbody for receiving oil from the interior of said-crankcase as the. gas pressure in.

as a rapid carrier of the oil through the feed line. The

second' method may embody additional check valve means as follows. Adjacent one end of the oil collector 25, a gas passage 45 is extended through the members 31, 32 and 33, to connect the interior of the crankcase 15 with the passage 41', and a yieldable valve means 46 is arrangedto close the lower end of the passage 45 during the suction cycle in the crankcase 15, but to permit a small flow of gas from the interior of the crankcase 15 into the passage-41 during the compression cycle in the crankcase 15. The valve means 46 is a flexible reed valve substantially the same as the reed valve 38' and'is secured in a position wherein its free end covers the lower end of the passage 45 by rivets 47. The result of the arrangement described is that consecutive quantities of oil and gas move through the duct 30 to the point of application of the oil.

1 Iclaim:

1.'In an automatic chain oiling means for a chain saw device having a two cycle engineprovided with a cylinder'having a fuel inlet port in the sidewall thereof and;a. fuel passage leading from the engine crankcase along .the side oflthe cylinder to the fuel inlet opening? said crankcase fluctuates dueto thereciprocation of the pistonof the engine; and acheck .valve connected to said gas passage for preventing flow of gas from said duct throughpsaid gas passageinto said crankcase.

3. In an automatic chain oiling means for a chain saw device having a two cycle engine providedwithan oil-. fuel receiving crankcase: an oil collector communicating with said crankcase comprising. an oilabsorbent body having a face thereof exposed to the interior of said crankcase and a wall formingv an oil collectingcharnber adjacent another face of said absorbent body,.said chamber having an opening for oil adapted to betconnected' to a duct for carrying oil to the saw chain; check. valvemeans for preventing reverse flow through saidch'amber; and means for admitting spaced quantitieszof air into saidduct to separate the oil flow therein into spaced quantities.

4; A device as defined in claim 3 whereinxsaid'means for admitting spaced quantities of air. to. saidduct comprises means forming a port connecting said. duct with the interior of said. crankcaseindependently of said absorbent body, andvalve means for controlling the-flow of air through said port.

5. In an automatic oiling device for-use with an internal combustion engine: an oil collector communicating with a crankcase of said engine, said collector having an outlet opening adapted to be connectedto a duct for carrying the oil away from said collector, means for feeding spaced quantities of air into said duct to separate the 'oil flow therein into spaced quantities, said means for. feeding spaced flows of air into said duct comprising means forming a port connecting said duct with the interiorof the crankcaseof the engine independently of said collector, and valve means for controlling the flow of air through said port.

References Citedin the file of this patent V UNITED STATES PATENTS 1,214,396 Wainwright Jan. 30,1917 2,288,426 Stack June 30, 1942 2,605,787 Kiekhaefer Aug. 5, 1952 2,682,259 Watkins June 29, 1954'

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