US3010538A

US3010538A - Chain saw lubricating system

Info

Publication number: US3010538A
Application number: US707321A
Authority: US
Inventors: Leonard M Strunk
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-01-06
Filing date: 1958-01-06
Publication date: 1961-11-28
Anticipated expiration: 1978-11-28

Description

Nov. 28, 1961 L. M. STRUNK 3,010,538

CHAIN SAW LUBRICATING SYSTEM Filed Jan. 6, 1958 2. Sheets-Sheet l INVENTOR. LEON HRD M. STRUNK.

F7 TTORNEV United States Patent 3,010,538 CHAIN SAW LUBRICATING SYSTEM Leonard lVI. Strunk, R.D. 4, Coatesville, Pa. Filed Jan. 6, 1958, Ser. No. 707,321 1 Claim. (Cl. 184-15) This invention relates generally to power-driven handsupported chain saws used primarily for felling and bucking trees, and more particularly to certainimprovements in that type of chain saw which is the subject of United States Letters Patent No. 2,748,810, issued to Leonard M. Strunk on June 5, 1956.

A principal object of the present invention is to provide for a chain saw of the type aforesaid improved means for delivering a lubricant to the saw bar.

Another object of the present invention is to provide for a chain saw of the type aforesaid a lubricating system including a pump operable for clearing the channel through which the lubricant is delivered to the saw bar should the same become clogged with saw dust or dirt.

Other objects and advantages of the present invention will appear more fully hereinafter, it being understood that the present invention consists substantially in the combination, construction, location and relative arrangement of parts, all as described in detail in the following specification, as shown in the drawings and as finally pointed out in the appended claim.

In the accompanying drawings:

FIGURE 1 is a side elevation of a chain saw constructed in accordance with and embodying the principles of the present invention.

FIGURE 2 is an enlarged view of the saw chain side of the saw, the saw bar and the saw chain being omitted.

FIGURE 3 is a front elevation of the saw with part in section, showing details of the arrangement for lubricating the chain.

FIGURE 4 is a side elevation of the fuel and oil tank.

FIGURE 5 is a fragmentary plan view as indicated by line 5-5 of FIGURE 4.

FIGURE 6 is a rear elevation of the fuel and oil tank.

FIGURE 7 is an enlarged section on line 7-7 of FIGURE 4.

FIGURES 8 and 9 are similar to FIGURE 7 but respectively show the condition of parts when there is a normal flow of oil and when the pump is being used to restore a normal flow of oil.

FIGURE 10 is a section on line 10-10 of FIGURE 7, showing the metering valve closed. 7

FIGURE 11 is an exploded view of the pump plunger and its head.

Referring to the drawings, the exemplary chain saw constructed in accordance with and embodying the principlm of the present invention comprises an internal combustion engine 10, a conventional carburator 11 positioned to the rear of and connected to the engine, a topmounted compartmented fuel and oil tank 12, a conventional magneto and engine starter within an air shroud 13 at one side of the engine, a side frame casting 14 at the opposite side of. the engine, a power shaft 15 extending through the side frame casting, a sprocket 16 and a clutch 17 mounted upon the power shaft, a forwardly projecting saw bar 18 supported by the side frame casting, a saw chain 19 trained over the sprocket and the saw bar, an encircling handle 20, and a rear supporting leg 21 disposed beneath the carburator.

The power shaft 15, which preferably is an extension of the engine crankshaft, projects through a centrally apertured well 22 formed on the inner or engine side of the side frame casting 14. The saw bar 18 is secured in flatwise assembly relation with the side frame casting 14 by a retainer plate 23 and a pair of studs 2424.

ice

The saw bar 18 is provided along its upper and lower longitudinally extending edges and along its rounded front edge with a continuously extending chain guiding channel, groove or slot 25, which slot is of adepth sufficient to accommodate therein the chain guide wings conventionally provided on the inner edges of the chain links and which guide wings, designated 26, are adapted for engagement with the teeth of the sprocket 16 for driving of the saw chain 19 about the saw bar 18. It will be appreciated that efficient operation of the saw requires that adequate provision be made for abundantly supplying the saw chain 19 and the guiding groove 25, in which the saw chain runs, with a suitable lubricant. The present invention meets this requirement in the manner now to be described.

The compartmented fuel and oil tank 12 includes, in addition to an oil reservoir, designated 27, for supplying lubricating oil to the chain-traversed saw bar 18, a compartment 27a in which is stored fuel for the engine 10. This tank is mounted so that the oil compartment 27 is elevated above the upper run of the saw chain during all normal positions of use of the saw. To this end, the tank 12 is provided along its bottom with a longitudinally extending supporting rib 28 which is embraced by a pair of angle members 29-29 suitably secured together by bolts 30. The oppositely extending base flanges of the angle members 29-29 are respectively secured, as by bolts 31 to a flat plate 32, which in turn is suitably secured to the engine body also by the bolts 31, the plate 32 being supported in suitably spaced relation to the engine body by spacers designated 33, embracing the shanks of the bolts 31 below the plate 32. Preferably, the tank mounting is such that the tank 12 is spaced fromand generally parallels the top side of the engine 10.

A fitting .34 is threaded into the front of the crankcase body, designated 35, of the engine, and a pressure, line 36 extends from the fitting 34 rearwardly under and then upwardly around the back of the crankcase body 35, within the air shroud 13. Then the line 36 extends through the air shroud 13, makes a loop 37 and connects to a check valve 38, which latter is threaded into the roof of the oil reservoir 27, near the partition which sepa-' rates the oil and fuel compartments. The line 36 serves to place the interior of the engine casing in communication with the oil reservoir 27. Since, in the normal operation of the engine 10, the interior of the engine casing is under pressure, in the order of 5 p.s.i., the oil reservoir 27 is likewise under pressure, in consequence of which oil is discharged from the oil reservoir 27 under pressure through an oil line section 39 connected into one side ofthe oil reservoir 27 and extending to the rear of the tank 12 for connection to unitary means, generally designated 40, adapted for controlling the flow of oil.

Extending from the unitary control means 40 forwardly between the tank 12 and the engine 10, then transversely over the engine 10 and finally forwardly to a fitting 41 is a second oil line section 42. The fitting 41 is threaded into the inner end of a passage 43, which passage ex: tends through the casting 14 and communicates with the chain guide groove 25, as by suitable passages 44 formed in the saw bar 18. g

The unitary control means 40 comprises a main body 45 fitted to the rear of the tank 12 and secured thereto by a screw 45a and having formed therein an upstream oil passage 46, a downstream oil passage 47 axially aligned with the passage 46, a bore 48 normal to and extending laterally from between the passages aforesaid, and an oil passage 49 normal to and extending laterally from the downstream oil passage 47 in parallel spaced relation to the bore 48. The upstream and

downstream oil passages

46 and 47 communicate with the inner end of the bore 48 respectively through constricted passage por- 'ing off the supply of oil.

3

tions

50 and 51, and the downstream oil passage 47 communicates with the inner end of the oil passage 49 through a constricted passage portion 52.

Threaded into the outer end of the upstream oil passage 46 is a fitting 53, to which fitting the oil line sec-- tion 39 isconnected. Within this passage is a valve 54, which valve is seated over the outlet end of the fitting 53,, being yieldably secured in position by a compression coil spring 55. Threaded into the outer end of the downstream oil passage 47 is a plug 56,and within the oil passage 47 is a valve 57, which valve is seated over the constriction 51, being yieldably secured in position by a coil spring 58.

Threaded into the outer end of the bore 48 is a sleeve 59, through which sleeve slidably projects a plunger 60 that is provided with a head 61 slidably fitted in the bore 48. The sleeve 59 is provided with a bonnet 62 that overlies a suitable packing 63. Under the head 61 is a compression coil spring 64 that acts to bias the plunger 60 outwardly.

Threaded into the outer end of the oil passage 49 is an adapter 65, and threaded into the latter is a needle valve 66, which needle valve includes a main body 67, a stem 68, a bonnet 69, and an operating knob 70. The outlet end of the valve 66 is connected with the oil line section 42 through the medium of a fitting 71.

In the operation of the chain saw, the oil reservoir 27 is pressurized in the manner already described, in consequence of which oil flows from the oil reservoirand courses successively through oil line section 39, unitary control means 40, the second oil line section 42, the oil passage 43, and the oil passage 44 to the chain guide groove 25 of the saw bar 18. .It will be noted, of course, that the oil delivered to the chain guide groove 25 is not returned to the reservoir 27, and hence the lubricating system is of the open-loop or non-return type. The flow of oil may be regulated by manipulating the needle valve 66. a

, Normally, the pressure exerted by the oil upon the valves 54 and 57 is suflicient for unseating the same against the influence of the

coil springs

55 and 58, in consequence of which oil courses freely from the tank 12 to the saw bar 18 in the manner aforesaid. However, it frequently happens that the oil passage upon the downstream side of the unitary control means 40 becomes clogged with dirt, saw dust or other foreign matter, chok- In this event, the plunger 60 is depressed to thereby clear the oil line of the obstruction.

Initial movement of the plunger 60 removes the pressure from the valve 54, which latter then closes under the influence of the spring 55. Continued movement of the plunger 60 then forces the column of oil under the head 61 of the plunger downstream'past the valve 57, in consequence of which the obstruction is dislodged and ejected from the oil channel.

When the plunger 60 is released, it is moved outwardly under the influence of the coil spring 64. Initial movement of the plunger 60 causes a suction that tends to draw oil back through the valve 57, which is precluded oil line. In order to provide the necessary freedom of movement for the plunger 60, a bleeder opening 72 for ceptible of various changes and modifications which may be made from time to time without departing from the real spirit or general'principles of the invention. For example, while preferablythe oil supply is pressurized, oil could be delivered from the oil reservoir to the saw bar simply by gravity flow. In addition, hinged type check valves could be utilized instead of the ball and coil spring ty-pe check valves shown and described. Furthermore, the metering valve 66 and the check valve 57, while desirable, are not essential. Still further both check valves 54 and 57 could be eliminated and an ordinary manually operated valve substituted for the check valve 54. Accordingly, it is intended to claim the same broad- 1y as well as specifically as indicated by the appended claim. 7

What is claimed as new and useful is:

In a portable chain saw of the type powered by an internal combustion engine having a laterally projecting power take-oil shaft adapted for driving-an endless saw chain trained about a drive sprocket and a saw bar extending freely beyond the front end of said engine, an open-loop lubricating system for lubricating the saw chain and saw bar comprising, an oil reservoir, a pressurizing line communicating between said reservoir above the oil level and the interior of the engine housing to place the oil in the reservoir under greater than atmospheric pressure when the engine is operating, an oil line operatively connecting said reservoir with said saw bar for delivery of oil to the latter, a pair of spring biased check valves series connected in said oil line to permit oil flow therethrough in the same direction, said valves automatically closing under spring bias to prevent delivery of oil from said reservoir to the saw bar when the engine is not operating and opening to permit oil flow therethrough responsive to the increased oil pressure when the engine is operating, and a single action plunger reciprocable within a cylinder connected in said oil line between said unidirectional valves, said plunger being operative upon each. working stroke to close the upstream valve against the valve-opening force of the pressurized oil and simultaneously to force oil through the downstream valve and the portion of said oil line upon the downstream side of the latter to thereby clear the same of any obstruction that may be impeding the free flow of oil, and being operative upon each return stroke to close the downstream valve against thevalveopening force of the pressurized oil to thereby avoid drawing oil back into the cylinder and simultaneously to open the upstream valve to thereby draw a fresh supply of oil into the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,878,167 Muller Sept. 20, 1932 2,605,787 Kiekhaefer Aug. 5, 1952 2,748,810 Strunk June 5, 1956 2,840,035 La Porte June 24, 1958 2,944,538 Conway et a1. July 12, 1960 FOREIGN PATENTS 7 295,454 Switzerland May 1, 1954