Patent Publication Number: US-2023140601-A1

Title: Torque driver

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Application No. 63/263,454, filed Nov. 3, 2021, the entirety of which is hereby incorporated by reference. 
    
    
     FIELD 
     The present disclosure generally relates to torque drivers, and more particularly to torque drivers that limit the amount of torque delivered. 
     BACKGROUND 
     Torque drivers, such as screwdrivers, are used to rotate (e.g., screw or wrench) a component, such as a fastener (e.g., bolt, screw), nut, and the like. Often times, torque drivers are used to tighten and secure the component in place. In certain situations, it is desirable for the torque driver to limit the amount of torque applied to the component. 
     SUMMARY 
     In one aspect, a torque driver for rotating a component comprises a housing having opposite proximal and distal ends and a longitudinal axis extending between the proximal and distal ends. The housing defines an interior. The housing includes a first set of ratchet teeth in the interior. A drive connector is configured to be engaged by a drive device. The drive connector is coupled to the housing such that the drive connector and the housing rotate together when the drive connector is rotated by the drive device. The drive connector is adjacent the proximal end of the housing. An output drive is adjacent the distal end of the housing. The output drive includes a second set of ratchet teeth engaged with the first set of ratchet teeth of the housing. The first and second sets of ratchet teeth are sized and shaped to rotate relative to one another when torque imparted on the drive connector by the drive device exceeds a predetermined torque. The output drive includes a component driver in a fixed relation relative to the second set of ratchet teeth such that the component driver and the second set of ratchet teeth rotate together. The output drive is configured to be operatively connected to the component to rotate the component. A biasing member is disposed in the interior. The biasing member applies a biasing force that correlates to the predetermined torque against the output drive to bias the second set of ratchet teeth toward the first set of ratchet teeth. A torque adjuster is disposed in the interior of the housing. The biasing member has a proximal end engaged with the torque adjuster and a distal end engaged with the output drive. The torque adjuster is selectively movable along the longitudinal axis relative to the output drive to selectively change an amount of the biasing force to change the predetermined torque. 
     In another aspect, a torque driver for rotating a component comprises a housing having opposite proximal and distal ends and a longitudinal axis extending between the proximal and distal ends. The housing defines an interior. A drive connector is configured to be engaged by a drive device. The drive connector is coupled to the housing such that the drive connector and the housing rotate together when the drive connector is rotated by the drive device. The drive connector is adjacent the proximal end of the housing. A component driver is configured to be operatively connected to the component to rotate the component. The component driver is adjacent the distal end of the housing. A clutch assembly is operatively connecting the drive connector and the component driver such that the drive connector rotates with the component driver when the component driver is rotated by the drive device and torque imparted on the drive connector by the drive device is below the predetermined torque. The clutch assembly is arranged to permit the drive connector and the component driver to rotate relative to one another when torque imparted on the drive connector by the drive device exceeds the predetermined torque. The clutch assembly includes a torque adjuster disposed in the interior of the housing. The torque adjuster is engaged to and supported by the housing. The torque adjuster is selectively movable along the longitudinal axis relative to the housing to adjust the predetermined torque. 
     Other objects and features of the present disclosure will be in part apparent and in part pointed out herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective of a torque driver of the present disclosure; 
         FIG.  2    is a cross-section of the torque driver of  FIG.  1   ; 
         FIG.  3    is a perspective of a housing of the torque driver of  FIG.  1   ; 
         FIG.  4    is an exploded view of the torque driver of  FIG.  1   ; 
         FIG.  5    is a cross-section of a torque driver according to another embodiment of the present disclosure; 
         FIG.  6    is a cross-section of a housing of the torque driver of  FIG.  5   ; and 
         FIG.  7    is an exploded view of the torque driver of  FIG.  7   . 
     
    
    
     Corresponding reference numbers indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION 
     Referring to  FIG.  1   , a torque driver of the present disclosure is generally indicated by reference numeral  10 . The torque driver  10  is used to rotate components (not shown), such as fasteners (e.g., screws, bolts, etc.), nuts, etc. The torque driver  10  allows an operator or worker to torque the component to a preset or predetermined torque. The torque driver  10  is able to torque or rotate the component and then—once the predetermined torque has been reached—is inhibited from being able to further rotate the component. The torque driver  10  is configured to be operatively disposed between a drive device (not shown), such as a handle, wrench, power tool (e.g., power drill), and the like, and the component to torque the component to the predetermined torque. 
     Referring to  FIGS.  1 - 4   , the torque driver  10  includes a housing  12  having opposite proximal and distal ends. A longitudinal axis LA extends between the proximal and distal ends. The housing  12  defines an interior  14 . The interior  14  has an open proximal end at the proximal end of the housing. The housing  12  defines a longitudinal bore  16  extending distally from the distal end of the interior  14  to the distal end of the housing. The housing  12  includes a generally cylindrical wall  18 . The interior surface of the cylindrical wall  18  includes threading  20  (e.g., internal threading). 
     The torque driver  10  includes a fixed drive  22  coupled to the proximal end of the housing  12 . The fixed drive  22  includes a plug  24  with threading (e.g., external threading) for threadably coupling the fixed drive  22  to the housing  12  (via the threading  20 ). This allows the fixed drive  22  to be removed or decoupled from the housing  12 , for reasons that will become apparent. The torque driver  10  includes a retainer  26  for securing the fixed drive  22  to the housing  12 . In the illustrated embodiment, the retainer  26  comprises a retaining pin, such as a radially expandable spring pin (e.g., split spring dowel pin). The retaining pin  26  engages the housing  12  and the fixed drive  22  to inhibit the fixed drive from moving (e.g., rotating or unscrewing) relative to the housing. The retaining pin  22  is disposed in aligned openings  28  in the wall  18  of the housing  12  and extends through the interior  14 . The plug  24  includes one or more channels or recesses  30  sized and shaped to receive the retaining pin  22 . The retaining pin  22  is disposed in one of the channels  30  to prevent the plug  24  from rotating relative to the housing. In the illustrated embodiment, the plug  24  includes three channels  30  arranged in a spoke pattern so that regardless of how the plug  24  is threaded to the housing  12 , one of the channels will align with the openings  28 . The expandability of the retaining pin  26  secures the pin to the housing  12 . In operation, to remove the fixed drive  22 , the operator pushes the retaining pin  26  out of the housing  12  using any suitable tool and then unscrews the plug  24 . To attach the fixed drive  22 , the operator screws the plug  24  into the housing  12  and then pushes the retaining pin  26  into the aligned openings  28  and channel  30  aligned with the openings. Other configurations of the retainer are within the scope of the present disclosure. 
     The fixed drive  22  includes a drive connector  32 . The drive connector is configured to be engaged by or connected to a drive device (broadly, connect the torque driver  10  to a drive device). In the illustrated embodiment, the drive connector  32  comprises a socket engaging stud or tenon, such as a hexagon or square cross-sectional shaped stud. Other configurations of the drive connector are within the scope of the present disclosure. The drive connector  32  is adjacent the proximal end of the housing  12 . The drive connector  32  is coupled to the housing  12  such that the drive connector and the housing rotate together when the drive connector is rotated by the drive device. In the illustrated embodiment, the retainer  26  ensures the fixed drive  22  (e.g., drive connector  32 ) and the housing  12  rotate together. In other words, the fixed drive  22  and the housing  12  are rotateably fixed relative to one another. 
     The torque driver  10  includes an output drive  34  adjacent the distal end of the housing  12 . The output drive  34  includes a first clutch member or plate  36  and a component driver  38 . The first clutch member  36  is disposed in the interior  14  of the housing  12 . The first clutch member  36  (broadly, the output drive  34 ) can rotate relative to the housing  12 . The first clutch member  36  and the component driver  38  are coupled together such that the they rotate together. The component driver  38  includes a drive shaft  40  extending from the first clutch member  36 . The drive shaft  40  is disposed in the bore  16  of the housing  12  and can rotate within the bore about the longitudinal axis LA relative to the housing. The component driver  38  projects distally from the distal end of the housing  12 . The component driver  38  is configured to be operatively connected to the component to rotate the component. In the illustrated embodiment, the component driver  38  includes a socket. The socket can be sized and shaped to receive (e.g., engage) the component or another tool (such as a screw driver bit or socket bit) that engages the component. Other configurations of the component driver are within the scope of the present disclosure. For example, the component driver can include any suitable driver, such as the socket, a flat head screwdriver, a Philips head screwdriver, etc., for operatively connecting to the component. 
     The first clutch member  36  includes a set of ratchet teeth  42 . The ratchet teeth  42  face distally. The ratchet teeth  42  are arrange circumferentially around the drive shaft  40 . Each tooth  42  includes a ramp and a flat. The ramp is oriented at a shallow angle to a plane normal to the longitudinal axis LA and the flat is generally parallel to the longitudinal axis LA. Each tooth  42  may have a rounded or flattened tip. It is believed rounding or flattening the tips of the ratchet teeth  42  makes them more durable, extending the operational life of the torque driver  10 . 
     The torque driver  10  includes a second clutch member  44 . The first and second clutch members  36 ,  44  are arranged to rotate together when the torque imparted on the drive connector  32  by the drive device is below the predetermined torque and are arranged to rotate relative to one another when the torque imparted on the drive connector by the drive device is equal to or exceeds the predetermined torque. The second clutch member  44  includes a set of ratchet teeth  46 , which are generally a mirror image of the set of ratchet teeth  42  of the first clutch member  36 . The ratchet teeth  46  of the second clutch member  46  faced proximally. The ratchet teeth  46  are arranged circumferentially around the bore  16  of the housing  12 . Each tooth  46  of the second clutch member  44  includes a ramp and a flat and may have a rounded or flattened tip, as described above in relation to the teeth  42  of the first clutch member  36 . In the illustrated embodiment, the first and second clutch members  36 ,  44  are engaged with one another. Specifically, the first and second sets of ratchet teeth  42 ,  46  are engaged with one another. The first and second sets of ratchet teeth  42 ,  46  are sized and shaped to move (e.g., rotate) together, so that the drive connector  32  and component driver  38  rotate together, when the applied torque is less than the predetermined torque. The first and second sets of ratchet teeth  42 ,  46  are sized and shaped to move (e.g., rotate) relative to one another, so that the drive connector  32  and component driver  38  rotate relative to one another, when the applied torque is equal to or exceeds than the predetermined torque. 
     The second clutch member  44  rotates with (e.g., is rotateably fixed to) the housing  12 . In the illustrated embodiment, the second clutch member  44  (e.g., the set of ratchet teeth  46 ) are part of the housing  12  (the housing includes the ratchet teeth). That is, the second clutch member  44  is an integral part of the housing  12 . Desirably, the second clutch member  44  and the housing  12  are an integral, one-piece component, as illustrated. Similarly, the first clutch member  36  rotates with (e.g., is rotateably fixed to) the component driver  38 . Specifically, the component driver  38  is in a fixed relation relative to the set of ratchet teeth of the output drive  34  such that the component driver and the set of ratchet teeth rotate together. Desirably, the first clutch member  36  and the component driver  38  are an integral, one-piece component (broadly, the output drive  34  is an integral, one-piece component). Having the housing  12  and the output drive  34  be integral, one-piece components simplifies manufacturing and reduces assembly time by reducing the number of components that need to be manufactured and assembled. This also simplifies the operation of the torque driver  10  by having less parts than conventional torque drivers. The fewer the number the parts the less opportunity for something to go wrong. Other configurations are within the scope of the present disclosure. For example, in one embodiment, the first clutch member and the component driver may be separate elements coupled together, such as by welding or with a fastener. In one embodiment, the second clutch member and the housing may be separate elements as well. In this embodiment, the second clutch member is disposed in the interior of the housing and is constrained to rotate with the housing. For example, the second clutch member and the housing can be keyed so that they rotate together. In another example, the one of the second clutch member and the housing can include one or more projections and the other of the second clutch member and the housing can include one or more corresponding recesses. The projections mate with the corresponding recesses to inhibit the second clutch member and the housing from rotating relative to one another. 
     Referring to  FIGS.  2  and  4   , the torque driver  10  includes a torque adjuster  48  and a biasing member  50 . The biasing member  50  is disposed in the interior of the housing  12 . The biasing member  50  biases the first clutch member  36 , distally, toward the second clutch member  44 . In the illustrated embodiment, the biasing member  50  biases the output drive (e.g., set of ratchet teeth  42  thereof) into engagement with the second clutch member  44  (e.g., set of ratchet teeth  46  thereof). The biasing member  50  has a proximal end engaged with the torque adjuster  48  and a distal end engaged with the output drive  34  (specifically, the first clutch member  36 ). In the illustrated embodiment, the biasing member  50  comprises a coiled spring, although other configurations are within the scope of the present disclosure. The biasing member  50  applies a biasing force against the output drive  34  to bias the set of ratchet teeth  42  thereof toward (and into engagement with) the set of ratchet teeth  46  of the second clutch member  44 . The biasing force applied by the biasing member  50  correlates to the predetermine torque. The larger the biasing force, the larger the value of the predetermined torque. Likewise, the smaller the biasing force, the smaller the value of the predetermined torque. The torque adjuster  48  is disposed in the interior  14  of the housing  12 . Desirably, the torque adjuster  48  is entirely disposed within the interior  14  of the housing  12 , as illustrated, to prevent the torque adjuster from being inadvertently moved relative to the housing  12 , thereby inadvertently changing the predetermined torque (as described below). The torque adjuster is disposed between the output drive  34  and the fixed drive  22 . The torque adjuster  48  is arranged to adjust or change the value of the predetermined torque. Accordingly, using the torque adjuster  48 , the operator can change the predetermined torque. The torque adjuster  48  is selectively movable along the longitudinal axis LA relative to the output drive  34  (e.g., the first clutch member  36 ) and to the housing  12  to selectively change the amount of the biasing force to change the predetermined torque. The torque adjuster  48  is selectively movable toward the output drive  36  to compress the biasing member  50  to increase the biasing force and thereby increase the predetermined torque and selectively movable away from the output drive to permit the biasing member to expand to decrease the biasing force and thereby decrease the predetermined torque. The torque adjuster  48  is engaged to and supported by the housing  12 . The torque adjuster  48  includes threading (e.g., external threading) for threadably coupling the torque adjuster to the housing  12  (via the threading  20 ). The torque adjuster  48  includes a tool receiver configured to receive a tool, such as a screw driver or Allen wrench, to allow the operator to rotate the torque adjuster to change the longitudinal position of the torque adjuster relative to the housing  12 , and thereby change the predetermined torque. In the illustrated embodiment, the tool receiver comprises an Allen wrench opening or recess sized and shaped to receive an Allen wrench, although other types of tool receivers are within the scope of the present disclosure. 
     The torque driver  10  of the present disclosure has a simpler construction with a minimal number of parts (e.g., only six parts) compared to conventional torque drivers. As a result, the torque driver  10  is simpler to manufacture and quicker to assemble over conventional torque drivers. Accordingly, the torque driver  10  of the present disclosure does not include the more intricate and complicated workings of conventional torque drivers. In the present disclosure, the absence of an element or elements from the figures is intended to indicate such an element or elements is absent from the torque driver  10 . For example, as shown in  FIG.  2   , the biasing member  50  is the one and only element of the torque driver  10  disposed in the interior  14  of the housing  12  between the first clutch member  36  and the torque adjuster  48 . In another example, as illustrated, the torque driver  10  is free of an element disposed within the biasing member  50 , such as a shaft. However, it is understood that torque drivers having one or more elements than shown in the figures are within the scope of the present disclosure, including the scope as defined by the claims. 
     The first clutch member  36 , the second clutch member  44 , the torque adjuster  48  and the spring  50  form a clutch assembly (e.g., ratchet mechanism or torque limiting mechanism) of the torque driver  10 . Clutch assemblies of other configurations are within the scope of the present disclosure. The clutch assembly operatively connects the drive connector  32  and the component driver  38 . The clutch assembly is arranged such that the drive connector  32  and the component driver  38  rotate together when the torque imparted on the drive connector by the drive device is less than the predetermined torque and is arranged to permit the drive connector and the component driver to rotate relative to one another when the torque imparted on the drive connector by the drive device is equal to or exceeds the predetermined torque. In operation, the set of ratchet teeth  42  of the first clutch member  36  face and engage the set of ratchet teeth  46  of the second clutch member  44 . The two sets of ratchet teeth  42 ,  46  engage each other so that the output drive  34  rotates with the housing  12  when the torque imparted is less than the predetermined torque and disengage or slip past one another so that the output drive does not rotate with the housing (e.g., allow the housing to rotate relative to the output drive) when the torque imparted is equal to or greater than the predetermined torque. 
     In use, the operator operatively connects the component to be rotated to the component driver  38 , such as by engaging the component driver with the component or engaging a tool accessory (e.g., screw driver bit) coupled to the component driver with the component. After, the operator begins using the drive device to rotate the drive connector  32  (broadly, the torque driver  10 ), which rotates the component driver  38 , which rotates the component. At this time, the torque imparted is less than the predetermined torque. The rotation imparted on the drive connector  32  is transferred to the housing  12 , which is transferred to the output drive  34  and then to the component. In this case (when the imparted torque is less than the predetermined torque), the fixed drive  22 , the housing  12 , and the output drive  34  all rotate together. The torque driver  10  is generally used to tighten a component. Accordingly, as the operator continues to rotate the drive connector  32 , the resistance (e.g., resistance torque or back torque) imparted by the component against the component driver  38  increases. When this resistance reaches the predetermined torque, continued rotation of the drive connector  32  (broadly, the torque driver  10 ) causes the two sets of ratchet teeth  42 ,  46  to slide relative to each other (in particular, the second clutch member  44  rotates relative to the generally stationary first clutch member  36 ). At this time, the resistance from the component is greater than the biasing force of the biasing member  50 . As a result, the output drive  34  no longer rotates as the drive connector  32  and housing  12  continue to rotate. As the drive connector  32  and housing  12  (e.g., set of ratchet teeth  46  of the second clutch member  44 ) continue to rotate, the ramps of the ratchet teeth  42 ,  46  slide relative to one another. This causes the output drive  34  to move proximally, against the biasing force of the biasing member  50 , in the interior  14  of the housing  12 . As the drive connector  32  and housing  12  continue to rotate relative to output drive  34 , the ratchet teeth  46  of the second clutch member  44  rotate past one full tooth profile of the ratchet teeth  42  of the first clutch member  36  (e.g., each ratchet tooth  46  of the second clutch member  44  slides past a corresponding ratchet tooth  42  of the first clutch member  36 ). When this occurs, the biasing force of the biasing member  50  moves the output drive  34  distally to reseat or reengage the sets of ratchet teeth  42 ,  46 . As a result of this movement, an audible click is heard as the output drive  34  is forced against the housing  12 , thereby informing the operator that the predetermined torque has been reached. With the predetermined torque is reached, continued rotation of the drive connector  32  will continue to cause the output drive  34  and the housing  12  to rotate or slide relative to each other and produce additional audible clicks, as just described above. 
     In the illustrated embodiment, the clutch assembly (e.g., the ratchet teeth  42 ,  46 ) is unidirectional such that the output drive  34  and drive connector  32  can only rotate relative to one another in one direction. In this embodiment, the drive connector  32  can only rotate clockwise relative to the output drive  34 , which corresponds with the torque driver  10  being configured to tighten a component. When the drive connector  32  is rotated in the opposite direction (e.g., counter-clockwise), the output drive  34  always rotates with the drive connector. In this instance, the flats of the ratchet teeth  42 ,  46  engage each other so that the output drive  34  and drive connector  32  rotate together. The flats inhibit the ratchet teeth  42 ,  46  from being able to slide past each other when the drive connector  32  is rotated in the counter-clockwise direction. This allows the operator to use the torque driver  10  to remove or loosen a component, without worrying about the clutch assembly disengaging. 
     Referring to  FIGS.  5 - 7   , another embodiment of a torque driver according to the present disclosure is generally indicated at reference numeral  110 . The torque driver  110  of  FIGS.  5 - 7    is generally analogous to the torque driver  10  of  FIGS.  1 - 4    and, thus, for ease of comprehension, where similar, analogous or identical parts are used, reference numerals “100” units higher are employed. Accordingly, unless clearly stated or indicated otherwise, the above descriptions regarding the torque driver  10  of  FIGS.  1 - 4    also apply to the torque driver  110  of  FIGS.  5 - 7   . 
     In this embodiment, the clutch assembly of the torque driver  110  of  FIGS.  5 - 7    has a different configuration than the clutch assembly of the torque driver  10  of  FIGS.  1 - 4   . In this embodiment, the torque driver  110  does not have ratchet teeth. Instead, the torque driver  110  (e.g., the clutch assembly) includes a plurality of balls  145  (e.g., steel balls) disposed between the first and second clutch members  136 ,  144 . The balls  145  are disposed in the interior  114  of the housing  112 . The first clutch member  136  includes a set of recesses  143  (e.g., partial hemispherical recesses) and the second clutch member  144  includes a set of recesses  147  (e.g., partial hemispherical recesses) which face the other set. Each recess  143 ,  147  is sized and shaped to receive a portion of one of the balls  145 . 
     In operation, the clutch assembly of  FIGS.  5 - 7    operates in a similar manner to that of the clutch assembly of  FIGS.  1 - 4   . The balls  145  engage the first and second clutch members  136 ,  144  so that the output drive  134  rotates with the drive connector  132  and housing  112  when the torque imparted is less than the predetermined torque and disengage or slip past one another so that he output drive does not rotate with the drive connector and housing (e.g., allow the housing to rotate relative to the output drive) when the torque imparted is equal to or greater than the predetermined torque. In use, when the two sets of recesses  143 ,  147  are aligned with one another, the balls  145  are disposed in the recesses. In this position, the drive connector  132  and the component drive  136  (e.g., the first and second clutch members  136 ,  144 ) rotate together when the torque connector  110  is rotated by the drive device. At this time, the torque imparted is less than the predetermined torque. The rotation imparted on the drive connector  132  is transferred to the housing  112 , which is transferred to the output drive  134  (via the balls  147 ) and then to the component. In this case, the fixed drive  122 , the housing  112 , and the output drive  134  all rotate together. As mentioned above, as the operator continues to rotate the drive connector  132 , the resistance (e.g., resistance torque or back torque) imparted by the component against the component driver  138  increases. When this resistance reaches the predetermined torque, continued rotation of the drive connector  132  (broadly, the torque driver  110 ) causes the first and second clutch members  136 ,  144  to rotate relative to one another (specifically, the second clutch member rotates relative to the generally stationary first clutch member). At this time, the resistance from the component is greater than the biasing force of the biasing member  150 . As a result, the output drive  134  no longer rotates as the drive connector  132  and housing  112  continue to rotate. As the drive connector  132  and housing  112  continue to rotate, the recesses  147  of the second clutch member  144  move out of alignment with the recesses  143  of the first clutch member  136 . This causes the balls  147  to move (e.g., roll) out of the recesses  147  of the second clutch member  144  and/or the recesses  143  of the first clutch member  136 . This causes the output drive  134  to move proximally, against the biasing force of the biasing member  150 , in the interior  114  of the housing  112 . As the drive connector  132  and housing  112  continue to rotate relative to output drive  134 , the recesses  147  of the second clutch member  144  rotate past one full recess profile of the recesses  143  of the first clutch member  136  (e.g., each recess  147  of the second clutch member  44  moves past a corresponding recess  143  of the first clutch member  136 ), and the recesses and balls  145  become realigned. When this occurs, the biasing force of the biasing member  150  moves the output drive  134  distally to reseat or reengage the sets of recesses  143 ,  147  with the balls  145 . As a result of this movement, an audible click is heard as the output drive  134  is forced distally against the balls  145 , thereby informing the operator that the predetermined torque has been reached. With the predetermined torque is reached, continued rotation of the drive connector  132  will continue to cause the output drive  134  and the housing  112  to rotate relative to each other and produce additional audible clicks, as just described above. 
     In this embodiment, the clutch assembly is unidirectional such that the output drive  134  and drive connector  132  will rotate relative to one another when the predetermined torque is reached regardless of which direction (e.g., clockwise or counter-clockwise) the drive connector (broadly, the torque connector  110 ) is rotated. In addition, it is believed the balls  147  provide a more durable configuration due to the lack of sharp edges in the clutch assembly. 
     It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. 
     When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     In view of the above, it will be seen that the several objects of the disclosure are achieved and other advantageous results attained. 
     As various changes could be made in the above products without departing from the scope of the claims, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.