US2741276A - Automatic lubricator for power driven chain saw - Google Patents

Description

April 10, 1956 H. E. WARREN AUTOMATIC LUBRICATOR FOR POWER DRIVEN CHAIN SAW Filed April 23, 1953 OIL RESERVOIR MMW III" V 11/, \\\Q\ .mA

INVENTOR Y E, WAR RE/V ATTORNEYS fa /Va United States Patent f AUTOMATIC LUBRICATOR F OR POWER DRIVEN CHAIN SAW Henry E. -Warren, Ashland, Mass., assignor to Lombard Governor Corporation, Ashland, Mass., a corporation of Massachusetts Application April 23, 1953, Serial No. 350,631

2 Claims. Cl. 143-32 My present invention relates to power driven chain saws, particularly those of the portable type. It aims to extend the life and improve the operating efiiciency of such saws by equipping them with built-in means whereby adequate lubrication may be constantly afforded automatically especially for the saw chain and operatively associated elements.

In the drawings illustrating by way of example one embodiment of the invention:

Fig. l is a perspective view of a typical portable chain saw unit incorporating the invention;

Fig. 2 is a sectional view in a plane through the axis of the saw chain drive sprocket and shaft, upon a larger scale; and

Fig. 3 is a sectional view corresponding to a portion of Fig. 2 upon a still larger scale.

The invention is applicable generally to power driven chain saws whether of the type having an electric motor or that having an internal combustion engine as the prime mover or power source. The saw unit selected for purposes of illustration in Fig. 1 comprises an internal combustion engine indicated generally at E integrated into a supporting frame including a transmission housing 2 and handle bars and positioners 3, 4. Adjustably fixed to the frame or housing is the cutter bar 5 presenting along its margin a continuous track for the endless saw chain 6. At the supported end of the cutter bar 5 the chain passes in driven engagement about the drive sprocket 11 fixed at the outer end of the drive shaft 10.

As seen in Fig. 2 the drive shaft is rotatably mounted in suitable bearings 7, S in the transmission housing 2 and has mounted on and keyed to it a rotary element 9 of the transmission whereby it is driven from the prime mover such as the rotor or crank shaft of the power source.

The saw chain drive shaft 10 is formed with a central bore extending from the inner or engine end, at the left in the views, the bore including an oil intake and driving or pumping portion 12 of calculated diameter and an oil conducting portion or duct 13, generally of somewhat less diameter. The oil-receiving bore 12 extends from the inner or entering end of the drive shaft to the location of the drive sprocket 11. The other or outer end of the shaft 10 is closed. One or more radial oil delivery ducts 14 extend from the outer bore portion 13 of the shaft and through the hub of and to the periphery of the sprocket 11, opening for egress of the oil between the sprocket teeth, preferably at the bottom of an inter-tooth space substantially as shown; Fig. 2.

The inner end of the shaft 10 terminates at and is enclosed by an oil chamber 15 in the saw frame or housing 2 and which communicates by a passage 16 with a framesupported oil reservoir 17 shown partly diagrammatically in Fig. 2; see also Fig. 1.

The inner and herein somewhat larger oil-driving portion 12 of the shaft bore receives and closely encompasses a relatively stationary helical stud or feed screw element 20. This non-rotary oil-director member 20 in cooperation with the rotary hollow shaft 10 serves to elfect oil 2,741,276 Patented Apr. 10, 1956 flow to the running saw chain and to restrain the oil at other times. Said oil conveyor and controller 20 has a shallow spiral thread of determined pitch for cooperation with the rotary shaft 10 in a manner to restrain the oil when the shaft is at rest, and to drive or pump the oil with a conveying action when the shaft is driving the saw chain. The outer diameter of the feed screw 20 loosely conforms to the cylindrical wall of the shaft bore portion 12 so that the spiral thread is in close proximity to or substantially in contact with it. The screw and bore diameters and the depth and pitch of the thread are calculated with reference to the designed speed of the shaft 10 and the rate of oil flow desired for the particular chain saw assembly.

The screw element 20 is held in operative position within the drive shaft 10 and is prevented from revolving with it by suitable mounting means which herein also affords ready access to and removability for the screw. In the illustrated example a squared portion 21 at the inner end of the screw 20 is set into a recess between lugs 22 on a threaded closure plug 23 in the housing 2, opposite the oil-chamber end of the drive shaft 10. The screw 20 is fixedly but demountably secured to the plug 23 as by a pin 24 passed through it and the ears 22 of the plug. Leakage of the oil to the outside of the drive shaft 10 is prevented by suitable packing 25 at the inner end thereof. The screw-supporting plug 23 also desirably is furnished with a neoprene or other oil-resistant washer 26.

The size of the feed screw 20 and of the shaft bore 12 in which it is received, and the depth and pitch of the screw thread also are selected with reference to the viscosity of the oil and the attendant temperature conditions. With the drive shaft 10 at rest the viscosity of the oil is an important factor in preventing fiow of the oil. During operation of the chain saw the same oil viscosity aids in pro moting the forward travel of the oil along through the spiral passageway formed between the conveying screw thread and the surrounding bore wall of the revolving drive shaft 10. The hand of the screw threading and the direction of rotation of the shaft 10 are matched so that with the shaft in motion the oil is driven forward toward and delivered to the sprocket wheel and thence to the saw chain and associated parts by the pumping or conveying action. In the illustrated example the screw 20 is of right hand, the oil advance is in a clockwise direction around it as viewed from the entering inner or left end of the screw in Figs. 1 and 2, and the rotation of the shaft 10 also is clockwise, as similarly viewed. The described relative dimensioning of the screw 20 and the shaft bore portion 12 and the depth and pitch of the screw thread are calculated with respect to the drive shaft speed, the oil viscosity and other expected circumstances of use so that a constant slow but adequate feed of oil to the sprocket wheel, the saw chain and its guide track about the cutter bar 5 is insured.

For the purposes of cleaning, the stationary oil feed screw 20 can readily be removed merely by backing out the mounting plug 23 which carries the feed screw 20 with it. Also by reason of the construction and arrangement of the illustrating example the rate of lubricant feed may be modified in accordance with seasonal or other operating conditions by similarly demounting and substituting another selectively available screw 20 with greater or less pitch and depth for the spiral passageway.

For some installations and operating conditions it is desirable to provide valve means for shutting off flow of lubricant when the chain saw or other machine equipped in accordance with the invention is at rest, and for opening the oil delivery duct at the start of and during operation. This applies more particularly with lubricants of relatively low viscosity or under high speed operation of the drive shaft such as the saw chain shaft 10 and attendant building up of ssubstantial pressures effective on the lubricant. In the illustrated embodiment of the invention such valving provision is shown, in this instance automatic and through the medium of the spiral feed screw element 29 itself. While the valving may be variously accomplished a simple and efficient structure for the purpose is had by utilizing the screw element 20 for the additional valving function.

Accordingly, as best seen in Fig. 2, the inner end of the screw element 20 is tapered to present a conical valve 27 and the bore 12 of the shaft is provided with a likeformed valve seat 28. The latter may be on an adapter *sleeve 29 inserted in the shaft bore subject to removal when the valve feature is not desired.

To afford the valving action the combined feed screw and valve element is given capacity for bodily shifting movement in the axial direction. Accordingly the outer squared portion 21 of the screw and valve element 2! adjacent the retaining pin 24 has the opening through which the pin passes somewhat elongated to provide a guide slot 21a, of sufi'icient extent axially to permit the element 29 to move to and from closing position at the valve seat 28. The outer end of the feed screw and valve element 20 is reduced or otherwise formed as at 31 for seating the inner end of a coil spring 32 positioned in a central recess 3i) formed in the closure plug 23, in prolongation of the bore 12 of the rotary shaft 10. Thus the feed screw-valve 20 is urged into the valve closing seated position as shown in Fig. 3, also Fig. 2.

When the machine or apparatus such as the chain saw of the drawings is started up for use the rotation of the shaft 19 in its encompassing relation to the non rotative feed screw and valve element 20 develops a pressure upon the lubricant within the shaft bore 12 and eifective on the feed-screw valve element 20 to shift it lengthwise against the loading of the spring 32. Thus the valve 27 is opened automatically and releases the lubricant for advance under the continuing influence of the feed screw within the rotating shaft 19, through the passages 13, 14 to the drive sprocket and saw chain or other parts to be lubricated. The spring 32 generally is relatively light and is selected to permit valve opening by the lubricant pressure available under the given operating circumstances. When the power is shut oh. and the drive shaft 10 comes to rest the valve member 27 automatically reseats under action of the valve spring 32 and counteracts any tendency of further flow of lubricant.

As apparent from the foregoing, the lubricant feeding feature as afforded by the spiral formation of the nonrotary element 20 in conjunction with the accompanying rotary shaft 10 may be utilized either with or without the provision for automatic shut-off and opening with respect to the lubricant supply.

periphery of the latter, an oil chamber on the frame and enclosing the bore entrance end of the shaft, a stud having a longitudinally advancing circumferential spiral formation extending into the shaft bore and proportioned relative thereto for flowing oil from saidcharnber during rotation of the shaft relative to the stud, a threaded plug on the frame at the oil-chamber end of the shaft and having a central bore supporting the stud non-rotatably but with capacity for axial shifting, a valve on the stud forward of the spiral formation, a seat for the valve in the shaft bore, and spring means in the plug bore urging the stud axially into valve closing position subject to automatic opening against the spring by oil pressure attendant on rotation of the shaft.

2. In a portable power-driven chain saw of the type comprising a frame supporting a prime mover, a cutter bar on the frame, a saw chain running on the cutter bar, and a rotary drive shaft on the frame operable by the prime mover and carrying a drive sprocket for the saw chain, automatic lubricating mechanism for the sprocket and the chain passing about it, said mechanism including a central bore in the drive shaft from one end to the sprocket and having a connecting radial passage opening to the sprocket periphery, an oil chamber enclosing said shaft end and supplied from a reservoir, a stud having an oil-feeding spiral thereon in and closely encompassed by the shaft bore and projecting at the oil-chamber end, the frame presenting a stationary wall opposite the oilchamber end of the drive shaft, a removable plug on said wall, means on the plug supporting the spiral-carrying stud non-rotatably in line with the axis of the shaft bore and also guiding the stud for limited bodily movement axially, said stud having the shaft-encompassed end formed as a valve and the shaft bore being formed with a seat therefor, and spring means on the plug loading the stud in valve-closing direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,125,917 Hanna Aug. 9, 1938 2,409,775 Mall et al Oct. 22, 1946 FOREIGN PATENTS 221,659 Switzerland Aug. 17, 1942 Mon-Mn"

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