U.S. patent number 3,680,608 [Application Number 05/007,569] was granted by the patent office on 1972-08-01 for chain saw.
This patent grant is currently assigned to Solo Kleinmotoren GmbH. Invention is credited to Eggert Bulk, Heinz Emmerich.
United States Patent |
3,680,608 |
Emmerich , et al. |
August 1, 1972 |
CHAIN SAW
Abstract
A portable chain saw having an elongated chain carrier about
whose circumferential edge portion a saw chain travels. Grip means
is rigid with the carrier for gripping by the hands of an operator.
An internal combustion engine is provided for imparting to the
chain its travelling movement along the edge portion of the
carrier. Connecting means connects the combustion engine with the
carrier so that they constitute a unit but without transmitting
vibrations between the combustion engine and the carrier.
Inventors: |
Emmerich; Heinz (Boeblingen,
DT), Bulk; Eggert (Sindelfingen, DT) |
Assignee: |
Solo Kleinmotoren GmbH
(Maichingen, DT)
|
Family
ID: |
5724201 |
Appl.
No.: |
05/007,569 |
Filed: |
February 2, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Feb 4, 1969 [DT] |
|
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P 19 05 301.15 |
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Current U.S.
Class: |
30/381; 30/383;
173/162.1 |
Current CPC
Class: |
B27B
17/0033 (20130101) |
Current International
Class: |
B27B
17/00 (20060101); B27b 017/02 () |
Field of
Search: |
;143/32 ;173/162 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schran; Donald R.
Claims
We claim:
1. A portable chain saw, comprising an elongated chain carrier
having a first longitudinal axis and a circumferential edge
portion; a housing rigidly connected with said carrier; a saw chain
mounted on said carrier for movement circumferentially of the same
along said edge portion; grip means rigid with said carrier for
gripping by the hands of an operator; an internal combustion engine
for imparting to said chain saw said movement and having a
crankshaft extending transversely of the elongation of said carrier
and a reciprocable piston having a second longitudinal axis normal
to said first axis; vibration-damping elements mounting said
combustion engine; and spacing means, comprising a spacing element
pivotally connected with both said housing and said combustion
engine so that said carrier and combustion engine are prevented
from relative movement longitudinally of said carrier and
transmission of vibrations between said combustion engine and said
carrier is suppressed.
2. A chain saw as defined in claim 1, said combustion engine having
a casing portion surrounding said crankshaft; further comprising a
bolt mounted on said housing; and wherein said spacing element is
pivotably mounted on said bolt and on said casing portion,
respectively.
3. A chain saw as defined in claim 1; and further comprising a
plurality of first auxiliary components rigidly connected with said
carrier, and a plurality of second auxiliary components rigidly
connected with said combustion engine so that the transmission of
vibration between said first and second auxiliary components is
precluded by the presence of said damping and said spacing
means.
4. A chain saw as defined in claim 3, wherein said second auxiliary
components include a blower for cooling air, an ignition
arrangement, a muffler, a starter unit, a centrifugal clutch, said
rotary pinion and a crankshaft casing.
5. A chain saw as defined in claim 4, wherein said first auxiliary
components include a fuel tank, an oil tank, a carburetor, an air
filter and covers for openings in said housing.
6. A chain saw as defined in claim 5, said housing and said
crankshaft casing being provided with juxtaposed wall portions; and
wherein said vibration damping elements are arranged between and
connected to said juxtaposed wall portions of said housing and said
crankshaft casing.
7. A chain saw as defined in claim 1; further comprising a
carburetor mounted on said housing; and a vibration damping fuel
conduit member connecting said carburetor with said cylinder of
said combustion engine.
8. A chain saw as defined in claim 1, and further comprising a
rotary pinion rotating with said crankshaft and transmitting motion
from said combustion engine to said chain.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a saw, and more
particularly to a chain saw. Still more specifically the invention
relates to a portable chain saw.
Portable chain saws are already known. Basically they comprise a
saw carrier which is elongated and has a circumferential edge
portion along which the saw chain travels which is driven by a
prime mover, usually an internal combustion engine which is united
with the carrier by means of a housing or analogous means. Hand
grips are provided so that the unit can be held by an operator. One
prior-art construction of such a portable chain saw has the
combustion engine and its fuel and oil tank as well as the hand
grips connected with one another into a rigid unit, to which in
turn the elongated chain carrier is rigidly connected. Vibrations
originating in the chain saw, usually from the combustion engine,
are transmitted in this construction to the arms of the operator
and thus to the body of the latter. Evidently, this at the very
least results in premature fatigue, and may even lead to damage to
the health of the operator.
This having been realized, attempts have been made to avoid the
problem. One such attempt mounts the handgrips via rubber mountings
to prevent vibration transmission through the handgrips. According
to one embodiment there are two handgrips provided which are
connected rigidly with one another and which are connected at three
points with the chain saw. The connecting means is in form of
rubber elements. However, it is evident that they cannot be very
soft--and therefore cannot provide significant damping of the
vibrations--because otherwise it would not be possible to properly
guide the saw. In particular it is difficult to provide such
vibration damping effect in this or in any known construction
because the vibrating portion of the chain saw, that is the portion
wherein the vibrations originate, has a significantly greater mass
than the handgrips themselves.
A further attempt to overcome the problem was made in an embodiment
in which the chain carrier and the combustion engine are connected
rigidly with one another. The thus obtained unit is mounted on a
housing by means of elastic mounting means, and the handgrips in
turn are rigidly connected with the housing. However, in this
embodiment also it is necessary that the force needed for guiding
the saw be transmitted from the handgrips via the elastic mountings
into the chain carrier, so that the vibration damping effect
obtained is only insignificant.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to provide a
portable chain saw which is not possessed of these
disadvantages.
More particularly it is an object of the present invention to
provide a portable chain saw which provides for an exact and easy
guidance of the saw by the operator but which prevents reliably and
to the maximum possible extent the transmission of vibrations
between the combustion engine and the chain carrier--and thereby to
the handgrips.
In pursuance of these objects, and others which will become
apparent hereafter, one feature of the invention resides in a
portable chain saw which, briefly stated, comprises an elongated
chain carrier having a circumferential edge portion, and a saw
chain mounted on the carrier for movement circumferentially of the
same along the edge portion. Grip means is rigid with the carrier
for gripping by the hands of an operator. An internal combustion
engine is provided for imparting to the chain its movement along
the edge portion.
According to the invention there is further provided connecting
means which connects the combustion engine with the carrier so that
they constitute a unit, but in such a manner as not to transmit
vibrations between the combustion engine and the carrier.
If a drive pinion for driving the chain is provided and mounted on
the crankshaft of the combustion engine, then the invention
provides that the longitudinal axis of the cylinder of the
combustion engine extend normal to the longitudinal axis of the
elongated chain carrier, that the rotating masses of the combustion
engine are balanced and the reciprocating masses are imbalanced,
and that the combustion engine is fixed against movement lengthwise
of the elongated chain carrier by the provision of a distance or
spacing element. In this manner the forces which tend to effect
such advancement, for instance the force of the travelling chain as
the same cuts through wood or the like, and which act upon the
internal combustion engine which is mounted in non-vibration
transmitting manner, cannot produce such displacement so that the
chain cannot lose its tension and become dislocated from the drive
pinion. The spacing or distance element is advantageously
configurated as a member which is pivotably mounted on the housing
of the saw and on the combustion engine. However, it may also be in
form of a first abutment provided on the housing and a second
abutment provided on the internal combustion engine and engaging
the first abutment if and when the combustion engine tends to move
lengthwise of the chain carrier. It will be realized that although
lengthwise displacement of the combustion engine with reference to
the chain carrier is not possible, displacement in direction
transversely to such lengthwise displacement--that is normal to
longitudinal axis of the carrier--remains possible so that the
transmission of vibration is precluded.
The vibration damping effect becomes the more pronounced, the
larger the mass of the non-vibrating components is with reference
to the mass of the vibrating components. It is therefore a concept
of the present invention to mount all possible auxiliary components
on the nonvibrating housing, that is all such auxiliary components
which must not be absolutely mounted rigid with the combustion
engine itself. Thus, there are mounted on the housing the oil and
fuel tanks, the chain carrier itself, and the handgrips.
Additionally, the carburetor for the combustion engine is mounted
on the housing and is connected with the cylinder of the combustion
engine via a vibration damping conduit member so that fuel can pass
from the carburetor to the cylinder of the combustion engine but
without the transmission of vibration between the two.
Advantageously the conduit member may consist of rubber or
generally an elastomeric material, and it fullfils the additional
function of providing thermal insulation between the cylinder and
the carburetor.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic fragmentary longitudinal section through a
chain saw embodying the invention, taken on the line I--I of FIG.
2;
FIG. 2 is a section taken on the line II--II of FIG. 1; and
FIG. 3 is a view similar to FIG. 1 but illustrating a further
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Discussing firstly the embodiment illustrated in FIGS. 1 and 2 it
will be seen that the novel chain saw basically is composed of two
major sections, namely a vibrating section and a non-vibrating
section. The vibrating section comprises an internal combustion
engine 1 of known construction, a crankshaft housing 2, a cylinder
3, a crankshaft 4, a chain drive pinion 5 with a centrifugal clutch
10 of known construction, a muffler 6, an ignition device 7, a
blower 8 for cooling air and a starter 9 of known construction.
The non-vibrating section consist essentially of a housing 11, an
elongated chain carrier 12 which is connected to the housing 11, a
fuel tank 13, an oil tank 14 and handgrips 15, 16 by which an
operator holds the chain saw when the latter is to be used. A cover
17 is provided which is fast with the housing 11 and which covers
the pinion 5 and the clutch 10; it also serves for mounting of the
chain carrier 12. A carburetor 18 and an air filter 19 with a cover
20 are also provided as part of the non-vibrating section.
These two basic sections, each composed of the above-mentioned
constituent components, are connected by connecting means which
secures them together so that they constitute a unit, namely a
portable chain saw, but which prevents the transmission of
vibrations between the vibrating and the non-vibrating section.
Specifically, the connecting means is in form of vibration-damping
elements 21, particularly of rubber but generally of any suitable
elastomeric material. The elements 21 are connected on the one hand
at the housing 11 and on the other hand at wall portions 22, 23 of
the crank shaft casing 2.
A distance member or spacing member 25 is provided which, despite
the mounting of the internal combustion engine 1 by means of the
vibration damping elements 21, prevents displacement of the
combustion engine 1 and the associated chain drive pinion 5 in
direction of the longitudinal axis 24 of the chain carrier 12. As
mentioned before such displacement could be the result of the
tensile forces exerted by the chain (which is illustrated
diagrammatically) as the same cuts through material such as wood.
The spacing member 25 in the embodiment of FIGS. 1 and 2 is in form
of a guide member 26 which is turnably secured on the one hand on a
bolt 27 mounted in the non-vibrating section, and on the other hand
on a neck portion 28 of the crankshaft casing 2 which is a part of
the vibrating section. However, displacement of the vibrating
section with reference to the non-vibrating section in direction
normal to the axis 24 are readily possible so that the
vibration-damping effect of the connecting means 21 is not
adversely affected by the presence of the member 26.
Coming to the embodiment illustrated in FIG. 3 it will be seen that
here the distance or spacing member 25 comprises an abutment 29 on
the housing 11, which abutment is provided with a surface located
in a plane normal to the longitudinal axis 24 of the chain carrier
12. A second abutment 30 is provided on the crankshaft casing 2 of
the combustion engine 1 and cooperates with the abutment 29 in such
a manner that they contact one another if the combustion engine 1
tends to move in direction of the axis 24 of the chain carrier 12,
thereby precluding such movement.
The longitudinal axis 31 of the cylinder 3 of the internal
combustion engine 1 extends normal or at least substantially normal
to the longitudinal axis 24 of the chain carrier 12, and the
carburetor 18--which is sensitive to vibrations--is mounted on the
housing 11. To permit the flow of fuel from the carburetor 18 to
the cylinder 3 of the combustion engine 1, the two are connected
via a vibration damping elastic conduit member 32 which may consist
of rubber or a suitable synthetic plastic. The conduit member 32
thus not only serves a vibration damping function while also
permitting the flow of fuel from the carburetor 18 to the cylinder
3, but also prevents the transmission of thermal energy between the
combustion engine 1 and the carburetor 18.
According to the invention it is advantageous that the combustion
engine be so balanced that mass forces develop only in direction
normal to the longitudinal axis 24 of the chain carrier 12. This
provides for optimum damping, and for this purpose the rotating
masses of the crankshaft drive are balanced whereas the
reciprocating masses remain imbalanced.
By resorting to our invention we maintain a rigid connection
between the chain carrier and the handgrips 15, 16 and the direct
and precise guidance of the chain saw which is possible in this
manner, while at the same time precluding entirely or almost
entirely the transmission of vibrations between the internal
combustion engine and its associated auxiliary components, and the
non-vibrating section of the saw, including the handgrips, so that
no vibrations or only very insignificant vibrations can be
transmitted to the hands and arms of an operator.
With the construction according to the present invention the
internal combustion engine can freely vibrate with reference to the
non-vibrating components of the chain saw and the vibrating masses
are reduced to a minimum whereas the proportion of the
non-vibrating masses with reference to the vibrating masses is
increased.
According to the invention it is possible to mount the combustion
engine as "softly" as desirable for purposes of obtaining optimum
vibration damping, that is to construct the connecting means 21 in
such a manner that the combustion engine 1 can vibrate with
reference to the non-vibrating components of the chain saw to any
practicable extent, without adversely influencing the handling and
operation of the machine while the same is in use.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of constructions differing from the types described
above.
While the invention has been illustrated and described as embodied
in a portable chain saw, it is not intended to be limited to the
details shown, since various modifications and structural changes
may be made without departing in any way from the spirit of the
present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can by applying current
knowledge readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range of
equivalence of the following claims.
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims.
* * * * *