Abstract:
A hand-held circular saw which is characterized by a gasoline-powered, trigger-operated blade drive unit connected to a conventional circular saw by means of a specially-designed adaptor. In a preferred embodiment the circular saw is characterized by a circular saw blade rotatably mounted in a saw housing which is connected to a drive shaft housing and adjacent gear housing. The adaptor is secured inside the drive shaft housing, and the blade drive shaft extends from connection to a blade-driving gear train inside the gear housing, and through the adaptor and projects from the drive shaft housing. The blade drive unit receives the protruding blade drive shaft, and is fitted with an attachment collar which removably receives the adaptor to connect the blade drive unit to the circular saw. The gasoline-powered circular saw is lightweight, efficient and suitable for outdoor home, farm or commercial use.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to powered hand saws and more particularly, to a hand-held, gasoline-powered circular saw which is characterized by a gas-powered, trigger-operated blade drive unit connected to a conventional circular saw by means of a specially-designed adaptor. In a preferred embodiment the blade drive unit is a conventional line-trimming apparatus drive unit, and the conventional circular saw is characterized by a circular saw blade rotatably mounted in a saw housing which is connected to a drive shaft housing and adjacent gear housing. The adaptor is secured inside the drive shaft housing and includes a circular adaptor base which is typically bolted to the drive shaft housing interior, and a shaft cylinder extends from the adaptor base. The blade drive shaft connects in conventional fashion to a blade-driving gear train located inside the gear housing, and extends from the gear housing through the adaptor base and shaft cylinder, respectively, of the adaptor and projects from the drive shaft housing. The blade drive unit receives the protruding blade drive shaft and is fitted with an attachment collar which removably receives the adaptor, to connect the blade drive unit to the circular saw. The gasoline-powered circular saw is lightweight, efficient and suitable for outdoor home, farm or commercial use. 
     Electric circular saws are widely used in the construction industry, as well as in private workshops and homes. Since most electric circular saws require a power cord which must be plugged into a power source for operation of the saw, the saws are not truly portable and cannot be used under inclement weather conditions without jeopardizing the safety of the saw operator. These problems are particularly apparent when operation of the saws is needed for construction of roads, highways, bridges or other outdoor structures. Moreover, battery-powered saws can be adversely affected by moist or cold weather, and re-charging of the batteries can be problematic when the construction site is in a remote location with respect to a suitable battery-charging facility. 
     2. Description of the Prior Art 
     Various gas-powered saws, as well as adaptors for inter-conversion of gas-powered chain saws and circular saws, are known in the art. U.S. Pat. No. 4,121,336, dated Oct. 24, 1978, to Ellis R. Loyd, describes a “Combination Power Saw and Chain Saw and Adaptor”, for converting a gasoline or electric circular saw to a chain saw, and vice-versa. The adaptor is characterized by a rectangular plate to which is attached a blade guard for receiving the conventional frame plate and blade of a chainsaw, which frame plate houses a drive sprocket for the chainsaw blade. After the blade of a conventional circular saw is removed from the circular saw frame, the circular saw frame is mounted on the rectangular plate and the saw drive shaft, connected to the engine inside the circular saw frame, is extended through an opening in the blade guard to engage the drive sprocket. The chainsaw blade is driven on the chainsaw frame plate as the circular saw engine is operated. An “Adaptor to Convert a Chain Saw to a Circular Saw” is detailed in U.S. Pat. No. 4,850,109, dated Jul. 25, 1989, to Michael A. Kerwin. The adaptor is characterized by a cylindrical collar which is secured by means of a washer and nut to the clutch housing and hub of the chain saw. A concentric opening extends through the collar, and has a ribbed, reduced diameter portion for receiving the clutch hub of the chainsaw and a threaded, enlarged diameter portion for receiving a threaded shaft extension plug. The shaft extension plug includes a face plate and a threaded shaft which extends concentrically from the face plate, for receiving a circular saw blade and a nut for securing the circular saw blade on the shaft. U.S. Pat. No. 4,876,797, dated Oct. 31, 1989, to Alvaro Zapata, details a “Reduced Vibration Portable Gas Operated Hand Saw” having a housing fitted with a carburetor and an engine, a handle which is mounted at one end of the housing and is provided with a trigger coupled to the carburetor, and a saw blade mounted at the other end of the housing. A worm gear, engaged by a centrifugal clutch which is driven by the engine, drives a rotatable shaft to which the saw blade may be keyed for rotation. Fans rotate with the clutch and saw blade, for cooling purposes. Anti-vibration elements are provided to isolate the handle and trigger from the engine. A rubber mount is interposed between the engine and housing to isolate engine vibration from the saw blade housing, saw plate, handle and trigger. A “Gasoline Engine Powered Hand-Held Circular Saw” is described in U.S. Pat. No. 5,007,173, dated Apr. 16, 1991, to Robert E. Rush. The saw includes a gasoline-powered engine which is incorporated into the body or frame of a circular saw. The engine is preferably a two-stroke engine, and is connected to a crank shaft to which the circular saw blade is mounted typically through a centrifugal clutch for rotation therewith. A throttle trigger is typically connected to the engine for controlling the engine speed. A plate is preferably provided on the circular saw frame for resting the saw on the workpiece. 
     An object of this invention is to provide a hand-operated, gasoline-powered circular saw. 
     Another object of this invention is to provide a portable, hand-operated, gasoline-powered circular saw which is capable of being used under inclement weather conditions. 
     Still another object of this invention is to provide a circular saw characterized by a gasoline-powered, typically trigger-operated blade drive unit which is connected to a conventional circular saw by means of a specially-designed adaptor. 
     Yet another object of this invention is to provide a circular saw characterized by a conventional, gasoline-powered line trimming apparatus drive unit which is connected to a conventional circular saw by means of a specially-designed adaptor having an adaptor base for attachment to the circular saw and a shaft cylinder extending from the adaptor base for engaging the line trimming apparatus drive unit. 
     A still further object of this invention is to provide a hand-operated, gasoline-powered circular saw which is portable, lightweight, efficient and suitable for outdoor home, farm or commercial use. 
     SUMMARY OF THE INVENTION 
     These and other objects of the invention are provided in a gasoline-powered circular saw characterized by a gasoline-powered, trigger-operated blade drive unit which is connected to a conventional circular saw by means of a specially-designed adaptor. In a preferred embodiment the blade drive unit is a conventional, gasoline-powered, line-trimming apparatus drive unit, and the conventional circular saw is characterized by a circular saw blade rotatably mounted in a saw housing which is connected to a drive shaft housing and adjacent gear housing. The adaptor is secured inside the drive shaft housing and includes a circular adaptor base which is typically bolted to the drive shaft housing interior, and a shaft cylinder extends from the adaptor base of the adaptor. The blade drive shaft connects in conventional fashion to a blade-driving gear train located inside the gear housing, and extends from the gear housing through the adaptor base and shaft cylinder, respectively, of the adaptor and projects from the drive shaft housing. The blade drive unit receives the protruding blade drive shaft and includes an attachment collar which removably receives the adaptor, to connect the blade drive unit to the circular saw. The gasoline-powered circular saw is lightweight, efficient and suitable for outdoor home, farm or commercial 
    
    
     BRIEF DESCRIPTION OF DRAWING 
     The invention will be better understood by reference to the accompanying drawings, wherein: 
     FIG. 1 is a right side view of a preferred embodiment of the gasoline-powered circular saw of this invention; 
     FIG. 2 is an exploded view of the gasoline-powered circular saw illustrated in FIG. 1, more particularly illustrating typically removable connection of the blade drive unit component of the gasoline-powered circular saw, to the circular saw component by means of an adaptor; 
     FIG. 3 is a rear view of the circular saw component of the gasoline-powered circular saw, with the circular saw removed from the blade drive unit as illustrated in FIG. 2; 
     FIG. 4 is a rear view of the circular saw component of the gasoline-powered circular saw, removed from the blade drive unit, with the adaptor and a connector plate mounted on the circular saw component; 
     FIG. 5 is a left side view of the gasoline-powered circular saw illustrated in FIG. 1; 
     FIG. 6 is a front view of the connector plate component of the gasoline-powered circular saw, illustrated in FIG. 4; 
     FIG. 6A is a side view taken along lines  6   a - 6   a  of the connector plate illustrated in FIG. 6; 
     FIG. 7 is a side view of the adaptor component of the gasoline-powered circular saw; 
     FIG. 7A is a top view of the adaptor, taken along lines  7   a - 7   a  in FIG. 7; and 
     FIG. 7B is a bottom view of the adaptor, taken along lines  7   b - 7   b  in FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to FIGS. 1-3 and  5  of the drawings, in a preferred embodiment the gasoline-powered circular saw of this invention is generally illustrated by reference numeral  1 . The gasoline-powered circular saw  1  is characterized by a circular saw  2 , such as that removed from a conventional, electric-powered blade drive unit (not illustrated). The circular saw  2  includes a saw housing  3 , with a circular saw blade  11  rotatably mounted in the saw housing  3  on a saw blade shaft  12 , as illustrated in FIG.  5 . The saw housing  3  substantially encloses the continuous cutting edge  11   a  of the circular saw blade  11 , and leaves the cutting edge  11   a  of the circular saw blade  11  exposed at a cutting gap  3   a  in the saw housing  3 . The circular saw blade  11  extends through a blade slot (not illustrated), provided in a blade guide plate  13  which is rested on the board, lumber or other workpiece (not illustrated) being cut by the circular saw blade  11 , during operation of the gasoline-powered circular saw  1  as hereinafter further described. As further illustrated in FIG. 5, a plate support  18  projects upwardly from the blade guide plate  13 , adjacent to the front end thereof and is pivotally attached to the saw housing  3  at a pivot pin  19 . An arcuate adjustment bracket  14 , provided with an adjustment slot  15 , extends upwardly from the blade guide plate  13 , adjacent to the rear end thereof, and a bracket bolt  17  extends through a bracket arm  16 , provided on the saw housing  3 , and through the adjustment slot  15 , respectively. Accordingly, by loosening the bracket bolt  17 , sliding the adjustment bracket  14  on the bracket bolt  17  while pivoting the plate support  18  on the pivot pin  19 , and re-tightening the bracket bolt  17 , the blade guide plate  13  can be adjusted on the saw housing  3  to support the circular saw  2  on the lumber or workpiece, depending on the angle of the lumber or workpiece as hereinafter described. 
     As illustrated in FIG. 1, a drive shaft housing  5  and gear housing  10  are provided on the rear surface of the saw housing  3 , and a saw handle  4  additionally connects the saw housing  3  with the drive shaft housing  5 . As illustrated in FIG. 3, the drive shaft housing  5  includes a circular housing rim  6  which circumscribes a housing opening  5   a  of the drive shaft housing interior  5   b . A housing grate  48  separates the gear housing  10  interior (not illustrated) from the drive shaft housing interior  5   b , and a circular adaptor seat  45  having multiple seat flanges  46  projecting therefrom in circumferentially-spaced relationship with respect to each other, is secured to the interior housing grate  48  of the drive shaft housing  5 . A blade drive shaft  8  is connected in conventional fashion to a blade drive gear train (not illustrated), provided inside the gear housing  10  for driving the circular saw blade  1  inside the saw housing  3  upon rotation of the blade drive shaft  8 , as hereinafter described. The blade drive shaft  8  extends from the gear housing  10  and through the housing grate  48 , adaptor seat  45 , housing interior  5   b  and housing opening  5   a , respectively, and protrudes from the drive shaft housing  5  as illustrated in FIG.  2 . As further illustrated in FIG. 3, a cylindrical spacer  9  is typically mounted on the blade drive shaft  8 , inside the housing interior  5   b  and adjacent to the adaptor seat  45 , for purposes which will be hereinafter further described. 
     Referring again to FIGS. 1,  2  and  5  of the drawings, as illustrated in FIG. 2 the circular saw  2  is operably connected to a gasoline-powered blade drive unit  22  by means of a connecting adaptor  31 , specially designed for the purpose and hereinafter further described. The blade drive unit  22  is typically a gasoline-powered line trimming apparatus drive unit and includes an engine housing  23  which houses a conventional, gasoline-powered line trimming apparatus engine (not illustrated), and the engine housing  23  is typically fitted with multiple heat vent openings  24  for venting excess heat generated by the operating engine. A fuel tank  27  is typically mounted on the bottom of the engine housing  23  for containing gasoline for fueling the engine. A blade drive handle  25  extends upwardly typically from the rear surface of the engine housing  23 , and is fitted with a power switch  50  for starting the engine, and a finger-actuated throttle trigger  26  for engaging the engine in blade-driving configuration. A drive shaft receptacle  28  extends from the front of the engine housing  23 , and is fitted with a split attachment collar  29  having a pair of adjacent collar flanges  30  (one of which is illustrated in FIG.  2 ). As hereinafter further described, an Allen screw (not illustrated) is threaded through aligned screw openings  43 , provided in the adjacent collar flanges  30 , to facilitate tightening the attachment collar  29  around the connecting adaptor  31  and securing the blade drive unit  22  on the circular saw  2 . 
     Referring again to FIGS. 1-4 and to FIGS. 6-7B of the drawings, the connecting adaptor  31  of the gasoline-powered circular saw  1  is typically constructed from stainless steel and, as particularly illustrated in FIG. 7, includes a circular adaptor base  32 , with multiple base flanges  33  extending therefrom in substantially spaced-apart relationship with respect to each other around the circumference of the adaptor base  32 . As illustrated in FIGS. 7A and 7B, an adaptor bolt opening  36  extends through each base flange  33 , and an adaptor mount bolt  44  is extended through each adaptor bolt opening  36  as illustrated in FIG. 4, to secure the adaptor base  32  of the connecting adaptor  31  to the adaptor seat  45  (secured to the housing grate  48  inside the drive shaft housing  5 , FIG. 3) as hereinafter further described. As further illustrated in FIG. 7, a shaft cylinder  34  extends from the adaptor base  32 , and as illustrated in FIGS. 7A and 7B, a shaft bore  35  traverses the shaft cylinder  34  and extends through the adaptor base  32  of the connecting adaptor  31  for receiving the cylindrical spacer  9  (FIG. 3) and blade drive shaft  8  as the connecting adaptor  31  is mounted in the drive shaft housing  5 . 
     As illustrated in FIGS. 4,  6  and  6 A, after the connecting adaptor  31  is mounted inside the drive shaft housing interior  5   a , a substantially rectangular, typically stainless steel connector plate  37  is mounted on the drive shaft housing  5  of the circular saw  2 . Accordingly, bolts  41  are initially extended through respective plate bolt openings  39 , provided in the respective corners of the connector plate  37 , and threaded into respective registering housing bolt openings  7 , provided in the drive shaft housing  5  as illustrated in FIG. 3, to secure the connector plate  37  against the drive shaft housing  5 . The connector plate  37  is provided with a central shaft opening  38  for receiving the drive shaft receptacle  28  of the blade drive unit  22 , in assembly of the gasoline-powered circular saw  1  as illustrated in FIG.  2  and hereinafter further described. 
     Referring again to FIGS. 1-4 of the drawings, in assembly of the gasoline-powered circular saw  1 , the connecting adaptor  31  is initially secured to the adaptor seat  45  (FIG.  3 ), inside the drive shaft housing interior  5   b . This is accomplished by initially inserting the cylindrical spacer  9  (mounted on the blade drive shaft  8 ), into the shaft bore  35  (FIGS. 7A and 7B) of the connecting adaptor  31 , as illustrated in FIG. 2, and sliding the connecting adaptor  31  on the spacer  9  until the adaptor base  32  of the connecting adaptor  31  abuts against the adaptor seat  45 . The adaptor base  32  is then secured to the adaptor seat  45 , with the blade drive shaft  8  extending from the extending end of the shaft cylinder  34  of the connecting adapter  31 . Accordingly, the adaptor mount bolts  44  (FIG. 4) are extended through the adaptor bolt openings  36  (FIG. 7A, provided in the respective base flanges  33  of the adaptor base  32 ), and threaded through the respective registering bolt openings  47  (FIG. 3, provided in the respective seat flanges  46  of the adaptor seat  45 ). The connector plate  37  is then mounted on the drive shaft housing  5  as heretofore described with respect to FIG. 4, by extending the bolts  41  through the respective plate bolt openings  39  (FIG. 6, provided in the connector plate  37 ) and threading the bolts  41  into the respective registering housing bolt openings  7  (FIG. 3, provided in the drive shaft housing  5 ). Assembly of the gasoline-powered circular saw  1  is completed by attaching the blade drive unit  22  to the circular saw  2 . This is accomplished by initially inserting the blade drive shaft  8  (FIG. 2, protruding from the drive shaft housing  5 ), into the drive shaft receptacle  28  of the blade drive unit  22 , as the drive shaft receptacle  28  is extended through the shaft opening  38  (FIG. 6) of the connector plate  37  and the connector socket  29  is inserted in the housing interior  5   b . Accordingly, the Allen screw openings  43  (FIG. 2, provided in the collar flanges  30  of the attachment collar  29 ) are positioned in registry with an Allen screw opening  43   a , provided in the drive shaft housing  5  as illustrated in FIG.  2 . An Allen screw (not illustrated) is then extended through the Allen screw opening  43   a  and rotated in the clockwise direction through the Allen screw openings  43  using an Allen screw wrench (not illustrated), to thread the collar flanges  30  of the attachment collar  29  toward each other and tighten the attachment collar  29  around the shaft cylinder  34  of the connecting adaptor  31 . 
     Referring again to FIGS. 2 and 5 of the drawings, in typical operation of the gasoline-powered circular saw  1 , gasoline (not illustrated) of a suitable grade for fueling the engine (not illustrated, provided in the engine housing  23  of the blade drive unit  22 ), is poured in the fuel tank  27  of the blade drive unit  22 . After the saw operator (not illustrated) grasps the blade drive handle  25  of the blade drive unit  22  with one hand and the saw handle  4  of the circular saw  2  with the other hand, the blade guide plate  13  of the circular saw  2  is rested on the board or lumber (not illustrated) to be cut. The engine is energized by actuating the power switch  50 , and the engine is operated to engage the blade drive shaft  8  by depressing the throttle trigger  26 . Accordingly, the engine rotates the blade drive shaft  8  and cylindrical spacer  9  (FIG. 4) inside the shaft cylinder  34  of the connecting adaptor  31 , and transmits rotation through the gear train (not illustrated, contained inside the gear housing  10 ), to the saw blade  11 . This causes the saw blade  11  to rotate inside the saw housing  3  with a rotational speed which is directly proportional to the rotational speed of the blade drive shaft  8 , according to the degree of depression of the throttle trigger  26 . As the saw blade  11  rotates inside the saw housing  3  in the clockwise direction illustrated in FIG. 1, the saw operator advances the cutting gap  3   a  of the saw housing  3  toward the edge of the board or lumber (not illustrated), and the rotating saw blade  11  is caused to contact the board or lumber through the cutting gap  3   a,  beneath the blade guide plate  13 . As the gasoline-powered circular saw  1  is advanced over the board or lumber by using the blade drive handle  25  and saw handle  4 , the rotating saw blade  11  cuts through the board or lumber in conventional fashion, as long as the throttle trigger  26  remains depressed. Rotation of the saw blade  11  is terminated as desired, by releasing the throttle trigger  26 , and operation of the engine is terminated by depressing the power switch  50 . It will be appreciated by those skilled in the art that the blade guide plate  13  can be adjusted in conventional fashion on the saw housing  3 , as desired according to the angle of the board or lumber to be cut, by loosening the bracket bolt  17 , sliding the adjustment bracket  14  on the bracket bolt  17  while pivoting the plate support  18  on the pivot pin  19 , and re-tightening the bracket bolt  17  at the desired angle of the blade guide plate  13  on the saw housing  3 . 
     It will be appreciated by those skilled in the art that the gasoline-powered circular saw  1  of this invention is capable of being used at virtually any outdoor location for the construction of buildings, roads, bridges and the like, and under inclement weather conditions which would render operation of an electric-powered circular saw, hazardous to the saw operator. Moreover, it will be appreciated by those skilled in the art that the gasoline-powered circular saw  1  can be assembled using an existing circular saw  2  removed from the electrical blade drive unit of a conventional electric-powered circular saw, and an existing, gasoline-powered blade drive unit  22  removed from a conventional gas-powered line trimming apparatus. 
     While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.