Abstract:
An improved adjustable blade height and driving mechanism for a table saw, wherein the design is compact and the weight of the drive motor is not an applied load upon the operator rotating a hand crank or upon an actuating motor. The table saw comprises a main frame and a saw blade mounted to and driven by a belt driving mechanism comprising a pivotable frame that is pivotable about an axis parallel to the saw cutting axis, an electrical motor mounted stationary to the pivotable frame, and a blade height adjusting device to raise and lower the blade wheel relative to the work-piece support surface while the electric drive motor remains stationary.

Description:
BACKGROUND 
     Prior Art 
       [0001]    Belt driven devices that require variable height adjusting mechanisms such as those found in table saws are commonly configured whereby the drive motor and driven component are adjustably raised or lowered together by a hand crank or by an actuating electric motor. For applications that require the driven component to be driven at high torque and high speed, high powered motors that are typically heavy are used. Accordingly, the mechanism for raising and lowering the drive motor must overcome the heavy weight of the motor through either a high torque actuating motor or for the user to exert substantial effort when using a hand crank. The disadvantage of current belt driven configurations is further exacerbated by the large space required for the traditional arrangement of a belt driven device with an adjustable height feature. For applications where compactness is required, such as for portable equipment, the traditional belt drive configuration can be limiting if not impractical. It would be therefore advantageous to have a compact motor and belt arrangement where the weight of the motor is not an applied load on the actuator or on the operator turning the hand crank while raising and lowering the saw blade. A configuration where the motor is stationary but allows the driven component to be adjustably raised and lowered so that weight of the motor is not carried by the actuating mechanism allows the use of smaller, light weight, and inexpensive materials. 
       SUMMARY 
       [0002]    The object of the present invention is to overcome the above inadequacies by providing an improved adjustable blade height and driving mechanism through a compact arrangement whereby the drive motor is stationary in relation to the blade and the drive motor&#39;s weight is not an applied load on an operator turning a hand crank or on an actuating motor when raising or lowering the blade. The blade height and driving mechanism is simple in structure which allows for low manufacturing cost and is convenient to adjust and operate. 
         [0003]    To achieve the object, the present embodiment provides a blade height and driving mechanism for a table saw, wherein the table saw comprises a main frame assembly, a work-piece support platform mounted to the mainframe assembly and a saw slot and saw slot axis; a blade wheel mounted to and driven by a blade driving mechanism disposed under the work-piece support surface. 
         [0004]    The blade driving mechanism comprising a pivotal frame that is pivotable about an axis that is generally parallel to the saw slot axis, an electrical motor mounted substantially stationary to the pivotable frame, and an electrical motor having a drive pulley mounted to its output shaft. A belt driving system comprising a blade arm with a blade pulley rotatably mounted about an axis with the blade pulley connected to the blade wheel for driving the blade wheel to rotate, the blade arm pivotable about a pivot axis that is affixed to the pivotable frame; a counter arm having a counter pulley rotably mounted about an axis with the counter arm mounted coaxially with the blade arm and pivotable about the axis point; a drive belt interconnected to a drive pulley, the blade pulley, and the counter pulley. 
         [0005]    The blade height adjusting device is configured to raise and lower the blade wheel relative to the work-piece support surface. Preferably, the height adjusting device comprises a worm gear assembly configured to rotate the blade arm about its pivot axis to raise and lower the blade wheel, a gear of the worm gear assembly is attached to the blade arm, coaxially mounted to the pivot axis, such that the blade arm and gear rotate together, a worm of the worm gear assembly is operatively coupled to and driven by a motor that is controllable via a control panel. 
         [0006]    Preferably, the blade driving mechanism wherein a line passing through the blade arm pivot axis and blade pulley axis forms an angle with a line passing through the counter arm pivot axis and counter pulley axis with an angle almost equal to 90 degrees. The distance between the blade arm pivot axis and blade pulley axis is generally equal to a distance between the counter arm pivot axis and counter pulley axis. The blade arm and counter arm are configured to cooperatively rotate in unison such that when rotating the blade arm to raise the blade wheel, the blade pulley takes up additional slack in the drive belt extending from the drive pulley towards the blade pulley and the counter arm rotates to simultaneously counteract the effects of the blade pulley displacement on the drive belt by giving up slack in the drive belt extending from the drive pulley towards the counter pulley. When rotating the blade arm to lower the blade wheel, the blade pulley give ups lack in the drive belt extending from the drive pulley towards the blade pulley and the counter arm rotates to simultaneously counteract the effects of the blade pulley displacement on the drive belt by taking up additional slack in the drive belt extending from the drive pulley towards the counter pulley. The blade arm and counter arm are spring-biased which caused the blade arm to apply an opposing force against the counter arm. 
         [0007]    Using the adjustable blade height and driving mechanism described herein, the height of the saw blade can be adjusted easily with minimal force when compared to traditional table saw designs because the motor is stationary and its&#39; weight is not a burden when adjusting the blade height. The adjustable blade height driving mechanism of the invention is also compact and may be used in various table saws for the shop or for the work site where a portable design is best suited. 
     
    
     
       DRAWINGS—FIGURES 
         [0008]    The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is an isometric view of a table saw with a traversing blade constructed in accordance with one embodiment of the present disclosure; 
           [0010]      FIG. 2  is an isometric view of one suitable embodiment of the traversing mechanism, blade driving mechanism, and tilting mechanism of the table saw shown in  FIG. 1 ; 
           [0011]      FIG. 3  is a perspective view of one suitable embodiment of a traversing mechanism of the table saw shown in  FIG. 1 ; 
           [0012]      FIG. 4  is a partial isometric view of one embodiment of the blade drive assembly of the table saw shown in  FIG. 1 ; 
           [0013]      FIG. 5  is a so-called exploded view of the blade arm and counter arm of the blade drive assembly shown in  FIG. 4 ; 
           [0014]      FIG. 6A  is a partial side view of one suitable embodiment of the blade arm and counter arm configuration, wherein the blade wheel is in the lowered position; 
           [0015]      FIG. 6B  is a partial side view of one suitable embodiment of the blade arm and counter arm configuration, wherein the blade wheel is raised to its maximum height; 
           [0016]      FIG. 7  is a so-called exploded view of the tilt frame and its attached elements that supports the mounting of the blade driving mechanism and tilting mechanism; 
           [0017]      FIG. 8A  is a partial perspective view of the tilting mechanism of the table saw shown in  FIG. 1 , wherein the tilt frame is in its nominal operating position; 
           [0018]      FIG. 8B  is a partial perspective view of the tilting mechanism of the table saw shown in  FIG. 1 , wherein the tilt frame is in an angled position; 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 1  illustrates one suitable embodiment of a table saw  100  constructed in accordance with aspects of the present disclosure. The table saw  100  has a work-piece support platform  110 , a main frame assembly  111  adapted to support the work-piece support platform  110 , a plurality of support legs  112  adapted to support the main frame  111 , and a blade wheel  113 . The blade wheel  113  is translatable to a plurality of raised positions in the vertical direction relative to the work-piece support platform  110  and traversable to a plurality of positions in the horizontal direction generally parallel to the work-piece support platform  110  along a slotted hole  114 . A control panel  115  enables an operator to control the vertical, horizontal, and angular translations of the blade wheel  113  relative to the work-piece support platform  110 . The control panel  115  is mounted on the main frame assembly  111  and can easily be attached and detached, so that the user can operated the blade movements anywhere around the table saw  100 . 
         [0020]    The blade driving mechanism  300  will be shown as part of a table saw with a traversing mechanism  200  to show the reader how the compact arrangement of the blade driving mechanism  300  can easily be integrated into various cutting apparatuses. The components of the table saw  100  that drives the blade wheel  113  to rotate and provide the means to translate the blade wheel  113  in the vertical and angular directions are disposed under the work-piece support platform  110 . To that end, please refer now to  FIG. 2  where the table saw  100  is shown with the work-piece support platform  110  and support legs  112  removed. The table saw  100  comprises the traversing mechanism  200  for translating the blade wheel in the lateral direction  150 , the blade driving mechanism  300  used to rotate the blade wheel  113 , a height adjusting device  350  (see  FIG. 4 ) for vertically translating the blade wheel  113  relative to the work-piece support platform  110 , a tilt frame  400  for supporting various parts of the blade driving mechanism  300  and height adjusting device  350 , and a tilting mechanism  500  for angularly positioning the blade wheel  113  relative to the work-piece support platform  110 . 
         [0021]    Referring now to  FIG. 3 , the figure illustrates the assembly of the traversing mechanism  200  (blade driving mechanism  300 , tilt frame  400 , and tilting mechanism are not shown for the purpose of clarity). The main frame assembly  111  is composed of longitudinal members  111   a ,  111   b  that extend in the longitudinal direction  151  and lateral members  111   c,    111   d  that extend in the lateral direction  150 . The longitudinal members  111   a  and  111   b  are spaced apart in the lateral direction  150  and the lateral members  111   c  and  111   d  are spaced apart in the longitudinal direction  151 . The lateral members  111   c  and  111   d  are fixedly attached by fasteners, welding or any other suitable means to the longitudinal members  111   a  and  111   b.    
         [0022]    The main frame lateral members  111   c  and  111   d  form the bases of the linear guide rails  210  and  211  for the traversing mechanism  200 . The linear guide rails  210  and  211  are rigidly attached to the main frame lateral members  111   c  and  111   d,  respectively, and are configured generally parallel to the lateral direction  150 . 
         [0023]    The traversing mechanism  200  further includes a carriage assembly  212  slidably coupled to the linear guide rails  210  and  211  via a plurality of linear bearings  214 , a traversing motor  215  mounted to a traversing motor mounting frame  217  that is fixedly attached to the main frame longitudinal member  111   a,  a traversing threaded rod  218  coupled to a traversing motor output shaft  216  on one of its ends and coupled to a traversing hand wheel  219  on its other end, shaft mount bearings  220  and  221  for supporting the traversing threaded rod  218 , a vertical support plate  222  attached to a carriage extended member  213 , and a traversing nut  223  fastened to the vertical support plate  222  and threadably engaged with the traversing threaded rod  218 . 
         [0024]    The carriage assembly  212  is composed of a longitudinal member  212   c  and extended member  213  that extend in the longitudinal direction  151  and lateral members  212   a  and  212   b  that extend in the lateral direction  150 . The main frame assembly  111  and the carriage assembly  212  are configured and sized to allow the tilt frame  400  (shown in  FIG. 4 ) and its attached assemblies to translate laterally and angularly without coming into contact with the main frame assembly  111  in its predetermined range of motion. 
         [0025]    Also, as shown best in  FIG. 3 , the ends of the guide rails  210  and  211  terminates to a point before the main frame longitudinal members  111   a  and  111   b  to provide enough space in between the ends of the guide rails  210 ,  211  and the main frame longitudinal members  111   a ,  111   b  to facilitate installation or replacement of linear bearings  214 . 
         [0026]    In operation, the traversing motor  215  rotates the traversing threaded rod  218 , which in turn, moves the traversing nut  223 . The traversing motor  215  is selectively reversible so that the traversing threaded rod  218  can be rotated in either direction, thereby allowing the traversing nut  223  to transmit an actuating force on the vertical support plate  222 , that is attached to the carriage extended member  213 , to advance and retreat the carriage assembly  212  to a plurality of positions along the linear guide rails  210  and  211 . Alternatively, the traversing hand wheel  219  can be used to rotate the traversing threaded rod  218  to move the carriage assembly  212 , as the user desires. The traversing threaded rod  218  and traversing nut  223  acts like a jack screw, thereby, when the traversing motor  215  is in stop, it holds the carriage assembly  212  firmly in position. 
         [0027]    The linear actuator for traversing the carriage assembly  212  is shown as a threaded rod linear actuator and a nut. While the linear actuator is shown as threaded rod linear actuator, it may be any type of closed length linear actuator that can be attached to frame assembly  111  at both ends and can allow the carriage assembly  212  to translate linearly, including, for example, nut and screw, acme threaded rod, linear ball screw, linear track, rack and pinion, or linear slide. The traversing mechanism  200  may include two linear actuators of the same type, or each actuator may be of a different type. 
         [0028]    Referring now to  FIG. 4 , the blade driving mechanism  300  is mounted to the tilt frame  400  as seen from another direction. The blade driving mechanism  300  includes a blade driving motor  310  mounted to the tilt frame  400  via a blade drive motor mounting base  311 , a drive pulley  312  mounted to the blade driving motor output shaft, a blade arm  313  supporting a blade pulley  314 , a counter arm  315  supporting a counter pulley  316 , and a drive belt  317  wound around the drive pulley  312 , the blade pulley  314 , and the counter pulley  316 . 
         [0029]    The blade height adjusting device  350  is used to translate the blade wheel  113  from a stowed position to a plurality of raised positions relative to the work-piece support platform  110  (see  FIG. 1 ). The blade height adjusting device  350  includes a height adjusting motor  351 , an intermediate shaft  353  coupled to the height adjusting motor output shaft  352 , a worm  354  operatively coupled to the height adjusting motor output shaft  352  via the intermediate shaft  353 , a shaft mount  355  for supporting the intermediate shaft  353 , a shaft mount  356  integrated to the bracket  410  for supporting one end of the worm shaft  357 , and a worm gear  358  fixedly attached to the blade arm  313  and engaged with the worm  354 . 
         [0030]    Accordingly, the reader will see that the carriage assembly  212  is the framework that supports the tilt frame  400 , which the blade driving mechanism  300  and the height adjusting device  350  are mounted to. The tilt plate  400  is pivotably mounted to the carriage via pivot blocks  224  and  225  and pivot about an axis generally parallel to the guide rails  210  and  211 . 
         [0031]    In accordance with the aspects of the present disclosure, the blade arm  313  and counter arm  315  are configured to ensure a sufficient wrap-around frictional engagement of the drive belt  317  to the pulleys when adjusting the height of the blade wheel  113  between at least a raised position and a stowed position. To that end, please refer to  FIG. 5  where the configuration of the blade arm  313  and counter arm  315  will be described in greater detail. As best shown in  FIG. 5 , the blade arm  313  includes a blade shaft  319  rotationally coupled to the blade arm  313 . The blade pulley  314  is coupled to the non-threaded end of the blade shaft  319 . The blade shaft  319  includes a collar  320  integrated to the blade shaft  319  to axially retain the blade wheel  113  from moving in the longitudinal direction  153  and has a threaded end  321  sized to threadably receive a blade wheel nut (not shown) to retain the blade wheel  113  from moving in the longitudinal direction  151 . When the worm gear  358  is attached to the blade arm  313 , the hole  323  of the worm gear  358  coaxially aligns with the hole  324  of the blade arm  313 . The blade arm  313  and worm gear  358  are coaxially mounted to the axle  318  and pivot about an axis generally perpendicular to the face of the tilt frame  400 . 
         [0032]    The counter arm  315  includes a counter pulley shaft  325  rotationally coupled to the counter arm  315  and a counter pulley  316  is fastened to the counter arm shaft  325 . The counter arm  315  has a hole  326  sized to axially fit the axle  318  and cooperatively pivot with the blade arm  313 . 
         [0033]    The blade arm  313  has a lip  327  that extends from a vertical face of the blade arm  313 . The lip  327  is oriented in a generally diagonal direction. Similar to the blade arm  313 , the counter arm  315  also has a lip  328  and oriented in the same manner. The lip  327  and lip  328  face each other and are sized and spaced to receive springs  329  to bias the blade arm  313  and counter arm  315 , in an opposing manner, causing the blade arm  313  to apply a compressive force against the counter arm  315 . Each spring  329  is fastened to lip  327  on one end and fastened to lip  328  on its other end, preferably by fasteners. As shown best in  FIG. 4 , the blade arm  313  and counter arm  315  forms a generally L-shaped member, where each leg has generally the same length. The springs  329  provides the belt drive system with enhanced stabilization and tensioning by compensating for misalignment and belt lengthening. The blade arm  313  and counter arm configuration also facilitates the installation and removal of the drive belt  317  (see  FIG. 4 ) during assembly or servicing, where the user can push the counter arm  315  towards the blade arm  313  to loosen the wrap-around engagement of the drive belt  317  and thereby allow for installation or replacement. 
         [0034]    In operation, as depicted in  FIGS. 4-5 , the user employing the tool energizes the blade driving motor  310  via the control panel  115  (see  FIG. 1 ). As the blade driving motor  310  rotates the drive pulley  312 , the drive belt  317  causes the blade pulley  314  to rotate and thereby rotate the blade wheel  113  via the blade shaft  319 . In adjusting the height of the blade wheel  113 , the user energizes the height adjusting motor  351  via the control panel  115  (see  FIG. 1 ), which in turn, rotates the worm  354  via the intermediate shaft  353 . As the worm  354  rotates, the threads of the worm  354  engaged with the teeth of the worm gear  358  will cause the worm gear  358  to rotate. The height adjusting motor  351  is selectively reversible so that the worm  354  can be rotated in either direction. Since the worm gear  358  is fixedly attached to the blade arm  313 , the blade arm  313  will rotate in unison with the worm gear  358  and thereby raise or lower the blade wheel  113 , depending on the direction of rotation of the height adjusting motor  351 . 
         [0035]    With the blade driving motor  310  remaining substantially stationary relative to the tilt frame  400 , the blade arm  313  and counter arm  315  are configured to turn in unison such that, as shown in  FIG. 6A , when the blade wheel  113  is initially in the stowed position, when the user energizes the height adjusting motor  351  to raise the blade wheel  113 , the blade arm  313  will rotate in the counter clockwise direction causing the blade wheel  113  to rise. The upward swing motion of the blade arm  313  causes the blade pulley  314  to takes up additional slack in the drive belt  317  extending from the drive pulley  312  towards the blade pulley  314  and the counter arm  315  rotates to simultaneously counteracts the effects of the blade pulley  314  displacement on the drive belt  317  by giving up slack in the drive belt  317  extending from the drive pulley  312  towards the counter pulley  316 . 
         [0036]    As shown in  FIG. 6B , the blade wheel  113  is raised to its maximum height. In lowering the blade wheel  113 , the user energizes the height adjusting motor  351  to rotate the blade arm  313  in the clockwise direction. The downward swing motion of the blade arm  313  causes the blade pulley  314  to give up slack in the drive belt  317  extending from the drive pulley  312  towards the blade pulley  314  and the counter arm  315  rotates to simultaneously counteracts the effects of the blade pulley  314  displacement on the drive belt  317  by taking up additional slack in the drive belt  317  extending from the drive pulley  312  towards the counter pulley  316 . 
         [0037]    Referring now to  FIG. 7 , the tilt frame  400  and its attached elements supporting the blade drive assembly  300 , height adjusting device  350 , and tilting mechanism  500  will be described in detail. As best shown in  FIG. 7 , the tilt frame  400  includes the axle  318  that supports the blade arm  313  and counter arm  315  (see  FIG. 5 ) is fixedly attached to the vertical face of the tilt frame  400  and has a generally horizontal axis perpendicular to the vertical face of the tilt frame  400 . A cover plate  411  is fastened to the tilt frame  400  via mounting brackets  410 ,  417  and has a hole  412  sized to fit the end of the axle  318  to provide support for the free end of the axle  318 . The tilt frame  400  further includes a height adjusting motor mounting base  413  fixedly attached to the tilt frame  400  for supporting the height adjusting motor  315 , and a drive motor mounting base  311  for the blade driving motor  310  adjustably attached to the tilt frame  400  by fasteners extending horizontally through vertical slots  414  and through plate holes  415 . The tilt frame  400  has a curved slotted hole  416  oversized to allow the blade shaft  319  (see  FIG. 5 ) to move in its predetermined range of motion without contacting the tilt frame  400 . 
         [0038]    A tilting nut coupling plate  510  is pivotally joined to the tilt plate  400  via pivot frames  513  and  514 . The pivot frame  513  and  514  have pivot holes  511  and  515 , respectively, and are sized to fit pins  512  that are fixedly attached to the coupling base plate  510 . The coupling base plate  510  is retained by the pivot frame  513  to the tilt frame  400  by fasteners. 
         [0039]    Still referring to the embodiment of  FIG. 7 , the figure also illustrates the manner in which the tilt frame  400  is mounted on the carriage assembly  212 . The tilt frame  400  further includes pins  418  and  419  that are rigidly attached to the top corners of the tilt frame  400 . The tilt frame  400  is pivotably mounted on the lower part of the pivot blocks  214 L and  215 L and retained by the upper part of the pivot blocks  214 U and  215 U, respectively. 
         [0040]    Referring now to  FIGS. 8A and 8B , the tilting mechanism  500  is shown. The tilting mechanism  500  includes a tilting motor  516 , a tilting motor mounting plate  517  rigidly attached to the vertical support plate  222 , an intermediate shaft  518  coupled to a output shaft  519  of the tilting motor  516  , shaft support mounts  520  for supporting the intermediate shaft  518 , a universal joint  521  coupling the intermediate shaft  518  and a tilting threaded rod  522 , and a tilting nut  523  fastened to tilting nut coupling plate  510  and threadbly engaged with the tilting threaded rod  522 . The tilting mechanism  500  is used to tilt the tilt frame  400  between a nominal operating position, where the tilt plate is generally parallel to the vertical direction  154 , shown in  FIG. 8A , and at least a forty five degree position away from its nominal operating position, shown in  FIG. 8B . 
         [0041]    In operation, the tilting motor  516  rotates the tilting threaded rod  522 , which in turn, translates the tilting nut  523  along the axis of the tilting threaded rod  522 . The tilting motor  516  is selectively reversible so that the tilting threaded rod  522  can be rotated in either direction. The tilting nut  523  is coupled to the tilting nut coupling plate  510 , which is pivotally mounted to the tilt frame  400 . When the tilting threaded rod  522  rotates, the tilting nut  523  applies a push or a pull on the tilt frame  400  to rotate about its pivot axis, depending on the direction of rotation of the tilting motor  516 . 
         [0042]    The universal joint  521  and the tilting nut coupling plate  510  are configured to allow the tilting threaded rod  522  axis to gradually incline as the tilt frame  400  rotates away from it nominal operating position and to gradually recline as the tilt frame  400  rotates towards its nominal operating position. The tilting threaded rod  522  and tilting nut  523  acts like a jack screw; so when the tiling motor  516  is in stop, it holds the tilt frame  400  firmly in position. 
         [0043]    With respect to the above description, before explaining at least one preferred embodiment of the herein disclosed invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangement of the components in the following description or illustrated in the drawings. The invention herein described is capable of other embodiments and of being practiced and carried out in various ways which will be obvious to those skilled in the art. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0044]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing of other structures, methods and systems for carrying out the several purposes of the present disclosed device. It is important, therefore, that the claims be regarded as including such equivalent construction and methodology insofar as they do not depart from the spirit and scope of the present invention. 
         [0045]    While all of the fundamental characteristics and features of the invention have been shown and described herein, with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosure and it will be apparent that in some instances, some features of the invention may be employed without a corresponding use of other features without departing from the scope of the invention as set forth. It should also be understood that various substitutions, modifications, and variations may be made by those skilled in the art without departing from the spirit or scope of the invention.