US3759238A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Balancing system
Assignee: Outboard Marine Corp
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Filing: 1971-01-21
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Granted: 1973-09-18
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Expires: 1991-01-21
Abstract
Abstract Disclosed herein is a chain saw including a balanced two-stroke single cylinder engine in which balancing is provided, at least in part, exteriorly of the crankcase so as to maintain the volume of the crankcase as small as practical and thereby improve crankcase pumping action. More specifically, in the disclosed construction, rotary counterweights are carried at opposite ends of an engine block exteriorly of the crankcase. In one embodiment of the invention, one of the counterweights is driven by the same pinion which drives the chain sprocket. In another embodiment of the invention, one of the rotary counterweights is also a part of a lubricating oil pump.
Inventors
- 👤 F Irgens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:34
CPC Classifications
B; B27; B27B; B27B17/00; B27B17/0033; F; F02; F02B; F02B63/00; F02B63/02; F02B75/00; F02B75/007; F02B75/16; F16; F16F; F16F15/00; F16F15/22; F16F15/26; F16F15/264; F02B75/02; F02B2075/022; F02B2075/025; F02B61/00; F02B61/04; F02B61/045; F02B67/00; Y; Y10; Y10T; Y10T74/00; Y10T74/18; Y10T74/18056; Y10T74/18208; Y10T74/21; Y10T74/2173; Y10T74/2183; Y10T74/2184
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
366 words
An internal combustion engine comprising an engine block defining a crankcase and a cylinder extending from said crankcase, a piston reciprocable in said cylinder, a connecting rod connected to said piston, a crankshaft rotatably mounted by said engine block and including first and second end portions coaxial with said crankshaft rotational axis and extending exteriorly of said crankcase from the opposite sides of said engine block, a crank pin offset from the crankshaft rotational axis and located within said crankcase, and first and second crank cheeks located within said crankcase and connecting the ends of said crank pin to said first and second crankshaft end portions, said crank cheeks respectively including first and second counterweights located in offset relation to the crankshaft rotational axis and in diametrically opposite relation to said crank pin so as to each balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation, a first pinion mounted on said first crankshaft end portion exteriorly of said crankcase, a second pinion mounted on said second crankshaft end portion exteriorly of said crankcase, a first gear mounted on said engine block exteriorly of said crankcase and in mesh with said first pinion for rotation about an axis parallel to and spaced from said crankshaft rotational axis, said first gear including a third counterweight located so as to rotationally balance onehalf of said first and second crank cheek counterweights and so as to balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation, and a second gear mounted on said engine block exteriorly of said crankcase and in mesh with said second pinion for rotation about an axis located in the plane defined by said crankshaft axis and said first gear axis and parallel to and spaced from said crankshaft rotational axis on the opposite side thereof from said first gear axis, said second gear including a fourth counterweight located so as to rotationally balance onehalf of said first and second crank cheek counterweights and so as to balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation.
Claim 2
Dependent Claim
366 words
An internal combustion engine comprising an engine block defining a crankcase and a cylinder extending from said crankcase, a piston reciprocable in said cylinder, a connecting rod connected to said piston, a crankshaft rotatably mounted by said engine block and including first and second end portions coaxial with said crankshaft rotational axis and extending exteriorly of said crankcase from the opposite sides of said engine block, a crank pin offset from the crankshaft rotational axis and located within said crankcase, and first and second crank cheeks located within said crankcase and connecting the ends of said crank pin to said first and second crankshaft end portions, said crank cheeks respectively including first and second counterweights located in offset relation to the crankshaft rotational axis and in diametrically opposite relation to said crank pin so as to each balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation, a first pinion mounted on said first crankshaft end portion exteriorly of said crankcase, a second pinion mounted on said second crankshaft end portion exteriorly of said crankcase, a first gear mounted on said engine block exteriorly of said crankcase and in mesh with said first pinion for rotation about an axis parallel to and spaced from said crankshaft rotational axis, said first gear including a third counterweight located so as to rotationally balance onehalf of said first and second crank cheek counterweights and so as to balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation, and a second gear mounted on said engine block exteriorly of said crankcase and in mesh with said second pinion for rotation about an axis located in the plane defined by said crankshaft axis and said first gear axis and parallel to and spaced from said crankshaft rotational axis on the opposite side thereof from said first gear axis, said second gear including a fourth counterweight located so as to rotationally balance onehalf of said first and second crank cheek counterweights and so as to balance one-quarter of the shaking forces generated in the direction of the cylinder axis in response to piston reciprocation.
Claim 3
Dependent Claim
30 words
A chain saw including an internal combustion engine in accordance with claim 1 and a saw chain drive sprocket driven by one of said first and second crankshaft end portions.
Claim 4
Dependent Claim
28 words
A chain saw including an internal combustion engine in accordance with claim 1 and a saw chain drive sprocket driven by one of said first and second pinions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-17 | 1977-03-19 | 1977-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-17 | 1981-03-19 | 1981-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-17 | 1985-03-19 | 1985-09-18 | $7700.00 | Window Closed / Lapsed |