US3409056A - Portable power chain saw - Google Patents

Description

Nov. 5, 1968 A. RAUH 3,409,056

PORTABLE POWER CHAIN SAW Filed Sept. 15, 1965 2 Sheets-Sheet l Nov. 5, 1968 A. RAUH 3,409,056

PORTABLE POWER CHAIN SAW Filed Sept. 13, 1965 2 Sheets-Sheet 2 2i Fig.4

United States Patent 3,409,056 PORTABLE POWER CHAIN SAW Albrecht Rauh, Im Weinberg, Kleinheppach, Germany, as-

signor to Andreas Stihl Maschinenfabrik, Waiblingen, Germany Filed Sept. 13, 1965, Ser. No. 486,775 9 Claims. (Cl. 143-32) ABSTRACT OF THE DISCLOSURE Portable chain saw having a drive engine and a support handle unit having a transverse and a longitudinal handle rigidly interconnected with vibration damping bushings at the ends of the transverse handle and the rear end of the longitudinal handle which connect the handle unit to the saw structure and eliminate vibrations.

This invention relates to a portable power chain saw, which comprises two handles, which are mounted with vibration-damping mountings of resilient material on the front and rear portions of the motor unit, respectively.

It has been endeavored for a long time effectively to damp the vibration set up in power chain saws by highspeed drive motors because this continuous vibration has a highly adverse effect on the operation of the power chain saw and in many cases inflicts health damage on persons which are subjected to this stress for a prolonged time. It is known to use so-called sandwich-type vibration-damping mountings or other vibration-damping materials for mounting the handles of power saws on the machine frame. Such handles comprise usually a handle for the left hand of the operator and one for the right hand of the operator, and are secured to the front and rear portions of the motor unit, respectively. With this known mounting arrangement for the handles, an effective vibration damping can only be accomplished if the rubberlike resilient mounting between the handle and the motor unit is sulficiently soft so that the vibration generated by the motor is sufiiciently damped and is not transmitted to the handles.

On the other hand, if the rubberlike resilient mountings are soft as is required for an effective damping of vibration, a reliable control of the bodily movement of the power saw is no longer ensured although such control is essential. With vibration-damping mountings for handles of the type described hereinbefore, it has been found that the cutting forces, which act on a relatively long lever arm constituted by the guide bar for the .saw chain, laterally displace the motor unit relative to the handles owing to the soft mounting so that there is a lack of control of the bodily movement of the chain of the power saw during operation. For this reason, the known mountings described hereinbefore for the handles of portable power saws have become abandoned.

It is an object of the invention to provide for the bandies of power saws an arrangement which effects a strong damping of the undesired vibration and ensures that the connection between the handles on the one hand, and the motor unit and guide bar, on the other hand, has the rigidity which is required for a reliable operation of the power saw.

In a power saw which comprises two handles that are connected by vibration-damping mountings of resilient material to the front and rear portions of the machine, these conflicting requirements are fulfilled according to the invention in that a rigid connection is provided between the front and rear handles. The rigid connection between the front handle, for the left hand, and the rear handle, for the right hand of the operator, may have any desired design and location. It is merely essential that the two handles are rigidly interconnected so that the handles ice together with the rigid connectionform a stable frame, which is separate from the motor-unitand is connected to it by vibration-damping mountings, preferably at three points. Thus, the handles which are connectcd'in a rigid carrying frame are resiliently mounted on the motor at three points, which are spaced apart. l

In a preferred embodiment of the invention, two rubberlike resilient mountings are provided at the front end of the power saw, considered in the feeding direction, these mountings are spaced apart and extend transversely to the feeding direction, and the. third mounting for the rear handle is provided at the rear of the motor.

The two rubberlike resilient mountings at the front end may be connected to each other by a generally U-shaped handle, which extends transversely to theguide bar. This U-shaped handle has an intermediate grip portion, .to which a spar connected to the rearhandle-is rigidly secured. The invention provides a frame for mounting the motor unit, and the motor unit is supported in this frame in the main direction of movement of the vibration-gencrating motor members, such as the crankshaft, connecting rod, and pistons, by known vibration-damping resilient mountings, such as rubber mountings, sandwich-type mountings etc., at three points, which are spaced apart as far as possible. The provision of a rigid connection between the front and rear handles and the fact that the stable carrying frame, formed with the aid of this rigid connection, for the power saw is mounted preferably at three points ensures a surprisingly damping of the vibration transmitted from the motor to the strong handles as well as a sufficiently rigid connection between the handles and the power chain saw.

The invention will now be explained more fully with reference to the drawings, in which FIG. 1 is a perspective View showing a power chain saw, in which the guide bar and the saw chain guided by it are shown broken off at the forward end.

FIG. 2 is a side view of a chain saw having a different configuration from that of FIGURE 1 and looking in the direction of the arrow II in FIGURE 3.

.FIG. 3 is a top plan view looking in the direction of the arrow III in FIG. 2. 1

FIG. 4 is a front elevation taken in the direction of arrow IV in FIG. 3.

The power chain saw comprises in known manner a drive motor 1 not shown in detail and having a crankshaft, which is indicated only by its axis of rotation 2. The pulling handle for starting the drive motor is indicated at 3. A fuel tank 4 is disposed below the drive motor. The drive motor is combined with the fuel tank and accessories in a compact unit, which will be referred to as a motor unit. The guide bar 5 is connected to the front end of this unit. The saw chain 7 extends around this guide bar and is driven by the motor in the direction of arrow 6. The carrying handle 8 for the left hand of the operator is provided at the front end of the motor unit. The carrying handle 9 for the right hand of the operator is disposed at the rear end of the motor unit. A rigid connection 10 in the form of a connecting spar is provided between the front and rear handles 8 and 9 and together with the carrying handles 8 and 9 forms a rigid frame for the motor unit. This frame is secured to the motor unit by three points. In the embodiment shown by way of example, the front handle 8 is secured to. the motor unit at two points which are spaced apart transversely to the feeding direction of the power saw. The mounting 13 for the rear handle 9 forms the rear mounting. The mountings 11, 12, 13 are sandwich-type, rubberlike resilient mountings. The rubberlike resilient mountings 11 12, 13 are suitably arranged so that the lugs 14, 15 or 16 rigidly secured to the motor unit extend at right angles to the crankshaft axis 2. In other words, the axes gf these mountings are parallel to the axis of rotation 2 of the crankshaft. This orientation does not only ensure a strong damping but causes the rubberlike resilient mountings to be stressed mainly in' shears and less in compression or tension. It is essential that the rigid frame which has been providedfor the motor unit is connected to the motor unit by vibration damping mountings at three points, which are spaced apart. Two of the mountings may be disposed at the rear or front end of the motor unit and the third mounting must be disposed at that end which is opposite to the two other mountings. The rigid connectionwhich is provided according to the invention between the front and rear handles and the mounting of the resulting rigid carrying frame on the motor unit at three points result in a surprisingly strong damping. At the same time, the motor unit can vibrate freely without transmitting its vibration to the handles. In a development of the invention, the rigid connection or the frame including this rigid connection may carry parts of the power saw which need not be rigid with that part of the saw which carries the crankshaft, such as the air filter, carburetor or particularly the fuel tank, which is connected to the motor by a flexible tube. The rigid connection between thefront and rear handles of the power saw is shown in FIG. 1 to be disposed over the motor unit but may be disposed as desired, e.g. on the side of the motor block or below the same.

In the modification of FIGURES 2-4, the same invention principle is illustrated but the configuration of the chain saw is somewhat different. The numerals employed in FIGURES 2-4 are the same as that used on FIGURE 1 but have been increased by 20.

- It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions; and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

' What I claim is:

1. A'portable power chain saw which comprises; a saw chain, a motor unit having front and rear ends and a crankshaft between said ends operable to drive said chain, a chain supporting and guiding member connected to and extending from the front end of said motor unit, said chain being guided and supported by said member, a rigid handle unit having a plurality of spaced regions adapted for connection to correspondingly spaced regions on said motor unit, means connecting each said region of the handle unit to a pertaining region of the motor unit and including a resilient vibration damping element interposed between each pertaining pair of said regions, said handle unit comprising a transverse handle having two of said regions thereon at the ends thereof and a longitudinal handle fixed at one end to said transverse handle and having at the other end another of said regions, the said two of said regions on the handle unit being disposed on the side of the axis of said crankshaft toward one end of said engine and the said other of said regions on said handle unit being disposed on the other side of the axis of said crankshaft.

2. A portable power chain saw according to claim 1 in which said two regions on said handle unit are in the front side of the axis of said crankshaft while said other region on said handle unit is on the rear side of the axis of said crankshaft.

3. A portable power chain saw according to claim 1 in which the plane of said supporting and guiding member passes between the said two regions on said handle unit.

4. A portable power chain saw according to claim 2 in which the plane of said supporting and guiding member passes between the said two regions on said handle unit.

r 5. A portable power chain saw according to claim 1 in which said two regions on the handle unit are located at respectively different heights with regard to the horizontal when said saw is held with said supporting and guiding member in a vertical plane and extending horizontally outwardly from said motor unit.

'6. A portable power chain saw according to claim 1 in which each said region on said motor unit and on said handle unit comprises elastic element engaging surface means, said surface means extending substantially parallel to the plane of said supporting and guiding member and each said surface means on the motor unit being spaced from the pertaining said surface means on the handle unit in a direction perpendicular to said surface means to thereby form pairs of said surface means, and each said elastic element being interposed between and in engagement with a respective pair of said surface means whereby loads on said supporting and guiding member in the direction of the length there-of load said elastic elements in shear whereas loads on said supporting and guiding member perpendicular to the plane thereof loads said elastic elements in tension and compression.

'7. A portable power chain saw according to claim 6 in which said motor unit comprises a casing in which said motor is rigidly mounted and said regions on said motor unit are formed on said casing and comprise at least in part attachment members fixed to and projecting from said casing.

8. A portable power chain saw according to claim 6 in which said transverse handle is disposed at the front end of said motor unit and said longitudinal handle has its front end fixed to an intermediate point of said transverse handle and extends rearwardly therefrom to the rear end of said motor unit.

9. A portable power chain saw which comprises; a saw chain, a motor unit having front and rear ends and a crankshaft between said ends operable to drive said chain, a chain supporting and guiding member connected to and extending from the front end of said motor unit, said chain being guided and supported by said member, a rigid handle unit having a plurality of spaced regions adapted for connection to correspondingly spaced regions on said motor unit, means connecting each said region of the handle unit to a corresponding region of the motor unit and including a resilient vibration damping element interposed between each corresponding pair of said regions, said handle unit comprising a handle portion extending from the front end to the rear end of said motor unit and spanning the axis of said crankshaft, the forward end of said handle portion being connected to said motor unit through a pair of said corresponding regions on the side of said axis at the front end and through another pair of said corresponding regions on the side of said axis at the rear, said handle unit being also connected to said motor unit through a third pair of corresponding regions which are transversely spaced from and on the opposite side of the longitudinal center line from at least one of said first two pairs of regions.

References Cited UNITED STATES PATENTS 2,630,784 3/1953 Wallerstein 173162 X 3,140,746 7/1964 La Force 173-162 3,152,650 10/1964 Savidge 173162 3,224,473 12/1965 Dobbertin 143-32 FOREIGN PATENTS 565,783 11/1944 Great Britain.

DONALD R. SCHRAN, Primary Examiner.

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