Cutlery – Cutting tools – Saw
Reexamination Certificate
2001-05-11
2004-08-03
Dexter, Clark F. (Department: 3724)
Cutlery
Cutting tools
Saw
C030S381000, C188S065100
Reexamination Certificate
active
06769187
ABSTRACT:
TECHNICAL AREA
The present invention relates to chain saws, and more particularly to a system and method for applying braking to a cutter providing chain thereof.
BACKGROUND
Chain saws are well know means for cutting wood and the like and used properly can greatly reduce work, however, if not used carefully user injury can occur. As a result, safety features are desirable. Critical to safety is the capability of a chain saw system to stop a blade or cutter containing chain from moving when its motor is running, but the chain saw is not being applied to useful work. That is, efficient chain saw chain braking systems provide utility. In that light it is generally disclosed at this point that the present invention is a new braking system and method for braking chain saw chain motion.
With an eye to the present invention a Search of Patents was performed. A U.S. Pat. No. 5,101,567 to Cool was identified and describes a braking mechanism (
40
) and brake lever (
42
).
U.S. Pat. No. 3,793,727 describes a system in which two handles must be engaged against the chain saw frame to allow the chain to move. If either is released the chains stops.
U.S. Pat. Nos. 4,924,577 and 4,611,410 are included to show that the Chain Guide can be split in a way that allows extending the length thereof by adding sections.
U.S. Pat. No. 5,445,365 to Forderer shows application of a “dumbell” element, but its applied as a connection element, rather than a means to line-up ends of a Slit Chain Saw Chain Guide.
Even in view of the prior art, need remains for additional systems and methods to prevent, or stop chain saw chain motion once initiated.
DISCLOSURE OF THE INVENTION
Chain saws are very low torque, but high speed systems that derive cutting ability by generating high chain speed. That is, at a given torque, the cutting power is directly proportional to chain speed. It is therefore common to stall a chain saw in use due to minor chain pinching, taking too big a “bite” of, or causing too much force on, an item being cut. A similar result occurs when too high a chain tension is caused to exist, etc. It is this insight which led to the present invention, which is based in the fact that Chain Saws are constructed so that Blade Containing Links in a Chain Saw Chain are slideably mounted in an essentially centrally positioned Continuous Chain Channel Guide in Upper and Lower surfaces of an Elongated Support, via chain link mating elements, such that in use the Blades or Cutters on said chain can be caused to slideably travel in an elongated “circle” around said Upper and Lower surfaces of said Elongated Support. In use the outer Blades or Cutters are caused to contact something to be cut as said Chain is caused to so move. It is also noted that chain saw chains are comprised of links that are interconnected by means such as rivets and that there is some limited lateral “play” possible between links where adjacent Links are so joined to one another.
Now, the present invention innovation, in its preferred embodiment, involves cutting a Slit into the Continuous Chain Channel Guide Upper or Lower surface, (typically the Upper surface near an oil entry port), so that the centrally located Channel region on one side of the resulting Slit can be, when desired, dislocated with respect to the centrally located Channel region on the other side of said Slit.
The purpose is that so, in use, when it is desired to stop the Chain Saw Chain from moving, causing or allowing the identified central Channel dislocation causes spread of adjacent Chain Saw Chain Links, elements of which adjacent Links then collide with edges of a dislocated central Channel region. This, in combination with general frictional interaction caused between the chain and offset channel regions, one side of said Slit to the other, provides effective “Braking”, thereby causing the chain saw chain to stop motion.
The preferred embodiments provide for the natural positioning of the centrally located Channel region in one resulting side of the cut Upper or Lower surface of the Elongated Support to be dislocated, (ie. not aligned), with respect to the centrally located Channel region in the other side, such that a User must apply central Channel region aligning force to position the centrally located Channel regions on both sides of the Slit to be aligned, thereby allowing the Blade Containing Links in the Chain Saw Chain to slideably travel in an elongated “circle” around said Upper and Lower surfaces of said Elongated Support.
A preferred embodiment provides for a Dumbell shaped element to effect the alignment of centrally located Channel regions by a User applied force which causes said Dumbell element to move from being positioned on one side of the Slit to a position where it straddles the Slit.
One embodiment provides that the Elongated Support be cut in two places, thereby providing a segment thereof which can be positioned such that the centrally located Channel therein is caused to misaligned with centrally located Channel regions on either side of the two slits.
More precisely, the preferred embodiment of the present invention is a chain saw comprising a motor inside a housing, a blade or cutter providing chain saw chain comprised of links which include chain link mating elements, and an elongated support extending outward from inside said housing, said motor and chain saw chain being functionally interconnected such that operation of said motor applies motion producing force to said chain saw chain. While not of Patentable importance to the present invention, it is noted that the motor and chain saw chain typically are functionally interconnected inside said housing by a sprocket means which is affixed to the motor and engages the chain. Continuing, the outer perimeter surface of said elongated support has present an essentially centrally positioned continuous chain channel guide into which said chain link mating elements slideably insert. As with any conventional chain saw, during normal operation wherein the chain saw is used to cut such as wood etc., said chain link mating elements slide essentially freely through said continuous chain channel guide when forced to do so by operation of said motor. A distinguishing attribute of the preferred embodiment of the present invention, however, is that in a present invention chain saw the continuous chain channel guide has at least one slit present therein which allows effecting an offset of said continuous chain channel guide from one side of the slit to the other, said offset, when caused to be present by an operator, serves to impede the free slide-ability of chain link mating elements across said slit, and in combination with other caused friction based braking effects, prevents in the first place, or stops a chain saw chain's motion.
Again, preferred practice is to have the continuous chain channel guide be in an offset position, from one side of a slit to the other, unless a user purposely, by definite positive action, causes it to be aligned by the operation of an a continuous chain channel guide alignment means, thereby providing a chain saw which impedes the slideability of chain link mating elements across said slit until desired, and specifically effected by a user, and the preferred continuous chain channel guide alignment means is a dumbell shaped element slideably mounted in the elongated support, such that in use said dumbell shaped element causes alignment of the continuous chain channel guide means from one side of the slit to the other, when caused to be located so as to span said slit.
In a modified embodiment the present invention provides that there be a second slit in said continuous chain channel guide which allows effecting an offset of said continuous chain channel guide from one side of said second slit to the other.
Just as for the first slit, preferred practice is to require that said continuous chain channel guide be in an offset position, from one side of said second slit to the other, unless a user causes it to be aligned by operation of continuous chain channel gui
Dexter Clark F.
Welch James D.
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