Abstract:
A turbine tool design with a number of innovative aspects which may be incorporated into the tool individually or as a group. One aspect relates to improved speed control, based on an elastically deformable governor member disposed within the rotating impeller assembly and having a substantially uniform cross-section. Another aspect relates to a overspeed safety configuration that employs secondary, or “retro”, nozzles that are enabled when the elastically deformable governor member is removed from the impeller assembly. Another aspect relates to routing the motive fluid exhaust through the operator-adjustable throttle assembly. Still another aspect relates to an approach to axially preloading the bearings supporting the rotating shaft of the impeller assembly.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates generally to hand-held rotary tools, and more particularly to the construction of, and/or the control of pressurized fluid flowing through, a rotary turbine tool.  
           [0002]    Air motors are conventionally used to drive high speed hand-held rotary tools, such as grinders and drills, because the air motor is suitable for light work and relatively safe. Unfortunately, many air motors of the prior art have poor speed regulation, with speed tending to drop drastically in the face of torque loading. Efforts have been made to improve speed regulation, with less than ideal results. For instance, U.S. Pat. No. 3,071,115 to Schott discloses one prior art approach for controlling the speed of a pneumatic rotation motor. The Schott approach relies on mechanical flyweights for both a speed governor and an overspeed safety device. While both the Schott governor and the overspeed safety device are disposed within the motor, the Schott rotor design as a whole is rather complicated, requires a relatively large radial space, and is difficult to adapt to very fast rotating motors. Particularly in high speed applications, the centrifugal forces acting on the flyweights and other parts in the Schott design place high demands on the dimensions and material of the flyweight springs, etc., increasing costs.  
           [0003]    More recently, U.S. Pat. No. 6,241,464 to Huffaker discloses a rotary turbine tool with an approach to speed control that relies on the interplay of a complex elastomeric valve member and a plurality of valve guides to control airflow, with no back-up form of overspeed protection.  
           [0004]    Thus, there remains a need for alternate rotary tool designs, particularly for alternative hand-held rotary turbine tool designs.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides an improved hand-held turbine tool design with a number of innovative aspects which may be incorporated into the tool individually or as a group. One aspect of the present invention relates to improved speed control based on an elastically deformable governor member disposed within the rotating impeller assembly and having a substantially uniform cross-section. Another aspect of the present invention relates to an overspeed safety configuration that employs secondary, or “retro”, nozzles that are enabled when the elastically deformable governor member is removed from the impeller assembly. Another aspect of the present invention relates to routing the motive fluid exhaust through the operator-adjustable throttle assembly. Still another aspect of the present invention relates to a simplified method of axially preloading the bearings supporting the rotating shaft of the impeller assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 shows a perspective view of one embodiment of the hand-held turbine tool of the present invention.  
         [0007]    [0007]FIG. 2 shows a exploded view of a throttle assembly useful in the present invention.  
         [0008]    [0008]FIG. 3 shows another exploded view of the throttle assembly of FIG. 2.  
         [0009]    [0009]FIG. 4 shows a view of the relationship between an impeller assembly and a main body for one embodiment of the present invention.  
         [0010]    [0010]FIG. 5 shows an exploded view of an impeller assembly useful in the present invention.  
         [0011]    [0011]FIG. 6 shows a view of a manifold according to one embodiment of the present invention.  
         [0012]    [0012]FIG. 7 shows a view of the manifold of FIG. 6 with the governor removed.  
         [0013]    [0013]FIG. 8 shows an alternate “overhose” coupling of a hose to a throttle assembly. 
     
    
     DETAILED DESCRIPTION  
       [0014]    One embodiment of the hand-held turbine tool  10  of the present invention is shown in FIG. 1. The turbine tool  10  is pneumatically powered, typically by compressed air supplied via a hose  12  that is coupled to the housing  20  via hose coupler  14 . The housing  20  typically includes three parts: a main body  30 , a throttle assembly  100 , and a handle portion  40 . The housing  20  operatively supports a rotating impeller assembly  200  (see FIGS.  4 - 5 ), and defines a fluid flow path  18  therewith, as described more fully below. The rotation of the impeller assembly  200  rotates the drill bit, rotary file, or the like, mated to the operative end of the tool  10 , as is well known in the art. The supply of pressurized air to the impeller assembly  200  is controlled via the throttle assembly  100  of the housing  20 . Rotation of a portion of the throttle assembly  100  in one direction closes off the supply of pressurized air to the impeller assembly  200 , while rotation in the opposite direction opens the supply of air to the impeller assembly  200 . The distal handle portion  40  of the tool  10  allows for easy hand-held operation by a user.  
         [0015]    The main body  30  of the housing  20  is threadably coupled on one end to the throttle assembly  100 , and on the other end to the handle portion  40 . Preferably, the main body  30  is a hollow body with a tapered profile that tapers from the relatively larger diameter of the throttle assembly  100  to the narrower diameter of the handle portion  40 . The front of the main body includes an opening  32 , having a bearing, referred to as the rear bearing  34 , disposed therein. An elastically deformable cushion element  38 , typically in the form of an O-ring, is placed between the front (handle) side of the rear bearing  34  and a corresponding seating shoulder in the main body  30 . See FIG. 4. In addition, another cushion element  36  may be placed radially between the outer race of the rear bearing  34  and the main body  30 . The function of these cushions  36 , 38  is discussed further below. The main body  30  of the housing  20 , and particularly the rear bearing  34 , cooperates with the handle portion  40  to support the impeller assembly  200  for rotation.  
         [0016]    As mentioned above, the throttle assembly  100  regulates the flow of pressurized air from the hose  12  to the impeller assembly  200 . To accomplish this, the throttle assembly  100  may be composed of a stationary throttle base portion  110  and a throttle cap  140  rotatably coupled thereto, as shown in FIGS.  2 - 3 . The throttle base  110  includes a generally disc-shaped base  112  and a post  130  extending therefrom. The base  112  includes external threads  114  on its distal side for mating with the housing&#39;s main body  30 , a pin  116  on its proximal side, and a plurality of holes  118  that pass from one side of the base  112  to the other. In addition, the base  112  includes an outlet  120  aligned with the central axis of the throttle base  110 . The post  130  of the throttle base  110  extends away from the base  112  on the proximal side thereof, also along the central axis of the throttle base  110 . This post  130  includes a shoulder section  132  proximate the base  112 , and a hollow threaded section  134 . A passage  136  for the input of pressurized air is at least partially defined by the hollow. The passage  136  continues into the shoulder section  132  and terminates at a passage outlet  137  that is oriented generally radially outward. Located on the shoulder section  132  approximately 180° from the outlet passage  137  is a transfer passage  138 , angled downward and inward, and terminating at the throttle assembly outlet  120  on the distal side of the base  112 . The throttle assembly outlet  120  directs the pressurized air from the throttle assembly  100  into the impeller assembly  200 , and preferably extends at least partially into the impeller assembly  200  when the turbine tool  10  is assembled, but allows rotation therebetween.  
         [0017]    The throttle cap  140  includes a generally annular section  142  joining an embossment  150  with a peripheral wall  146 , thereby forming a generally C-shaped cross-section on its underside. The open space of this C-shaped cross-section may be referred to as the “muffle space”  148 . A plurality of exhaust holes (or “exhaust ports”)  144  extend through the annular section  142 , thereby connecting the exterior of the throttle cap  140  to the muffle space  148 . The embossment  150  includes an outer recess  152  on its outer perimeter that extends in an arc of approximately 90°. Located generally opposite this outer recess  152 , and on the interior surface of the embossment  150 , is a transfer recess  154  that extends in an arc of approximately 270°.  
         [0018]    Both the throttle base  110  and throttle cap  140  of the throttle assembly  100  are preferably made from a strong lightweight material, such as aluminum. However, it may be advantageous for the outlet  120  feeding the impeller assembly  200  to be formed at least in part by an inert made from a suitable low-friction plastic material, such as Teflon or nylon.  
         [0019]    The throttle cap  140  is joined to the throttle base  110  by sliding the appropriate portion of the post  130  through the center of the hollow embossment  150 , aligning the parts such that the pin  116  fits within the outer recess  152  of the embossment  150 , and thereafter screwing the hose coupling  14  onto the post  130 . Suitable O-rings (not shown) may be disposed at the base of the post  130  to mate with the embossment  150  of the throttle cap  140 , and at the interface between the peripheral wall  146  of the throttle cap  140  and the throttle base  110 , both with corresponding seating recesses as desired. There may also be a suitable O-ring (not shown) disposed at the interface of the post  130  and the throttle cap  140 , proximate the hose coupling  14 . In addition, there may be a suitable washer, such as a plastic washer  15 , disposed between the hose coupling  14  and the throttle cap  140  (see FIG. 1).  
         [0020]    The joining of the throttle cap  140  to the throttle base  110  forms an inlet airflow path  160  and an exhaust airflow path  170  within the throttle assembly  100 , with these airflow paths  160 , 170  jointly forming portions of the overall airflow path  18  of the turbine tool  10 . The inlet airflow path  160  flows through the passage  136  of the post  130  and out the passage outlet  137 , into the transfer recess  154  in the embossment  150  of the throttle cap  140 , across the transfer recess  154 , and into the transfer passage  138 , and then out the outlet  120  to the impeller assembly  200 . The exhaust airflow path  170  of the throttle assembly  100  flows through the holes  118  in the throttle base  110 , into the muffle space  148  formed on the underside of the throttle cap  140 , and then out the exhaust holes  144  of the throttle cap  140 .  
         [0021]    While the throttle cap  140  is rotationally coupled to the throttle base  110 , the degree of relative rotation therebetween limited by the interaction of the pin  116  and the outer recess  152  on the embossment  150 . It is intended that interior surface of the embossment  150  block the entrance to the transfer passage  138  when the throttle cap  140  is rotated with respect to the throttle base  110  such that the pin  116  is located towards one end of the outer recess  152 . In this “off” throttle setting, the flow path between the passage outlet  137  and the transfer passage  138  is blocked, cutting off pressurized airflow to the impeller assembly  200 . When the operator rotates the throttle cap  140  relative to the throttle base  110  such that the pin  116  is moved substantially towards the opposite end of the outer recess  152 , at least a portion of the entry to the transfer passage  138  in the throttle base  110  is thereby aligned with the transfer recess  154  in the embossment  150 . In this configuration, the passage outlet  137  is connected to the transfer passage  138  via the transfer recess  154  on the interior surface of the embossment  150 , allowing pressurized air to flow from the hose  12  to the throttle assembly outlet  120 , and therefore to the impeller assembly  200 . Thus, the supply of pressurized air from the hose  12  to the impeller assembly  200  may be throttled via the relative rotation of the throttle cap  140  with respect to the throttle base  110 .  
         [0022]    Referring to FIGS.  4 - 7 , the impeller assembly  200  includes a rotating impeller body  210 , a spindle (or “shaft”)  260  mated to the impeller body  210 , a sleeve assembly  270 , and a front bearing  280 . The impeller body  210  includes a manifold  220  and a cap  250 . The manifold  220  includes a central chamber  222  that connects to both primary nozzles  230  and to secondary nozzles  240 . Note that some embodiments of the present invention may have only one primary port  230  and no secondary ports  240 ; although a plurality of each in equal numbers is believed advantageous. The primary nozzles  230  include primary ports  232 , primary passages  234 , and primary jets  236 . Likewise, the secondary nozzles  240  include secondary ports  242 , secondary passages  244 , and secondary jets  236 . The primary nozzles  230  and secondary nozzles  240  may be constant width or may vary in shape so as to be subsonic or supersonic, as desired. As can be seen in FIGS.  6 - 7 , the primary nozzles  230  and secondary nozzles  240  need not be of the same size/shape; indeed, it is believed advantageous if the primary nozzles  230  are larger in size than the secondary nozzles  240 . In addition, the primary jets  236  and the secondary jets  246  may generally face each other at the exterior of the manifold  220 , or they may be spaced apart as desired. The primary nozzles  230  are oriented to urge the impeller body  210  to rotate in a first direction when pressurized air flows therethrough, while the secondary nozzles  240  are oriented to urge the impeller body  210  to rotate in a second direction, opposite the first direction, when pressurized air flows therethrough.  
         [0023]    The central chamber  222  may include a central circular recess area corresponding to the post  252  of the cap  250 , and be generally defined by a peripheral wall  224 . The ports  232 , 242  associated with the nozzles  230 , 240  are located at select locations along the peripheral wall  224 . As described above, the group of primary ports  232  correspond to the input ends of the primary nozzles  230  and the group of secondary ports  242  correspond to the input ends of the secondary nozzles  240 . The central chamber  222  may advantageously have a generally rectangular outline with rounded corners. The primary ports  232  may advantageously be located in the corners, with the secondary ports  242  being located mid-way along each side. See FIG. 7.  
         [0024]    Further, it may be advantageous to provide additional shallow recesses  228  at each corner, with these recesses  228  extending below the nominal “floor” of the chamber  222 . The “floor” between the recesses  228  may be thought of as a shelf  226  that runs along the interior of the peripheral wall  224 .  
         [0025]    The annular cap  250  has a generally smooth underside, with a hollow post  252  extending therefrom. The hollow post  252  is internally threaded and includes a inlet jet  254  oriented radially outward. The impeller body  210  is assembled and mated to the spindle  260  by securely threading the hollow post  252  of the cap  250  onto the threaded end  262  of the spindle  260 , capturing the manifold  220  against the proximal side of the inner race of rear bearing  34 . Suitable torque may be applied to the cap  250  through the use of a faceted embossment  256  on the upper side of the cap  250 , if desired. With the cap  250  screwed in place, the impeller body  210  is rotationally coupled to the spindle  260 , such that rotation of the impeller body  210  causes rotation of the spindle  260 . Air flow from the throttle assembly outlet  120  enters chamber  222  via the hollow post  252  and inlet jet  254 .  
         [0026]    The spindle  260  coupled to the impeller body  210  is supported for rotation by a front bearing  280  and the rear bearing  34 , with the outer race of the rear bearing  34  secured to the main body  30  and the inner race of the front bearing  280  secured to the spindle  260  via any known technique. The bearings  34 , 280  should be subjected to an axial preload, such as a preload of approximately four pounds, and may be conventional or thrust bearings as desired. This axial preload may be accomplished in some embodiments of the present invention via simple adjustment of the sleeve assembly  270 . The sleeve assembly  270  is disposed generally about the spindle  260  and may include a threaded portion  272  and a spacer portion  276  disposed between the threaded portion  272  and the front bearing  280 . As shown in FIG. 4, the spindle  260  extends forwardly out the opening  32  in the main body  30  of the housing  20  and through the threaded portion  272 . The opening  32  is interiorly threaded to mate with the threaded portion  272 . The threaded portion  272  includes external threads and optional flats for aid in screwing the threaded portion  272  into and out of the opening  32  in the main body  30 . When the threaded portion  272  is screwed out of the main body  30 , it will eventually push against the spacer portion  276 , forcing the spacer portion  276  to abut against the front bearing  280 . This action has the effect of axially displacing the impeller assembly  200  forward with respect to the main body  30 . This movement has the effect of bringing the forward portion of the impeller body  210  into contact with the back side of the rear bearing  34 , urging the rear bearing  34  to move forward relative to the main body  30 . Forward movement of the rear bearing  34  compresses the cushion  38 , the elastic properties thereof providing the axial preload to the rear bearing  34 . In addition, this axial preload is also applied to the front bearing  280  due to the now-fixed relationship between the impeller body  210  and the front bearing  280 , via the spindle  260 . When the desired amount of axial preload is reached, perhaps as measured by the torque necessary to unscrew the threaded portion  272 , a suitable lock nut  274  may be put in place against the front “nose” of the main body  30 . In this fashion, the effective length of the sleeve assembly  270  may be adjusted to apply the desired preload in a very simple manner.  
         [0027]    It should be noted that it is not necessary, or even desirable, for the sleeve assembly  270  to touch the spindle  260 , except through the outer race of front bearing  280 , so as to allow for free rotation of the spindle  260  without wearing against the sleeve assembly  270 . Further, the presence of cushion  36  helps discourage small relative movements of the outer race of the rear bearing  34  and/or a relatively non-wearing surface if such movements do occur.  
         [0028]    When the throttle is open, the pressurized air from the inlet airflow path  160  of the throttle assembly  100  is supplied to the impeller assembly  200 . The drive air flows from the outlet  120  of the throttle assembly  100  into the chamber  222  of the impeller body  210  via the inlet jet  254 . The pressurized air within the chamber  222  is restrained between the cap  250  and the manifold  220 , and is thereby directed from the chamber  222  to the nozzles  230 , 240 . Assuming for the moment that the pressurized air is leaving the impeller body  210  only through the primary nozzles  240 , the flow of air through the primary nozzles  240  causes the impeller body  210  to rotate, thereby rotating the spindle  260  in a “drive” direction. As the impeller body  210  sits mostly within the main body  30  of the housing  20  (see FIG. 4), the pressurized air exiting the impeller assembly  200  flows between the impeller assembly  200  and the main body  30  of the housing  20 . This “exhaust” air is routed out of the main body  30  via the holes  118  in the throttle base  112 , and from there to the exhaust holes  144  via the muffle space  148 . As can be seen, the impeller assembly  200  and the housing  20  cooperate to form an fluid flow path  18  within the turbine tool  10 , with this fluid flow path  18  including the inlet airflow path  160  through the throttle assembly  100 , the air flow path through the impeller body  210  (e.g., the central chamber  222 , the primary nozzles  230  (and perhaps secondary nozzles  240 )), flow through the cavity within the main body  30  surrounding the impeller body  210 , and the exhaust airflow path  170  within the throttle assembly  100 .  
         [0029]    In order to control the rotational speed, the impeller assembly  200  of the present invention advantageously includes an elastically deformable speed control member  300 , sometimes referred to herein as the governor. This governor  300  advantageously has a uniform cross-section, and may take the form of a common rubber-like O-ring. The governor  300  is disposed within the chamber  222  of the impeller body  210  and should be sized such that it preferably rests against the peripheral wall  224 , on the shelf  226  within the chamber  222 , except at the primary ports  232  leading to the primary jets  236  (e.g., the corners, see FIG. 6). The uniform cross-section of the governor  300 , in an undeformed state, may advantageously be equal to or slightly larger than the height between the self  226  and the underside of the cap  250 , so that flow “over” the governor  300  is prevented.  
         [0030]    At low rpms the pressurized air entering into the chamber  222  flows through the chamber  222 , around the governor member  300 , such as through the recesses  228  proximate the primary ports  232 , through the relatively substantial gap between the governor  300  and the primary ports  232 , and then to the primary jets  236  via the primary ports  232  and primary passages  234 . With the governor  300  against the peripheral wall  224  of the chamber  222 , particularly in the neighborhood of the secondary ports  242 , the secondary ports  242  are directly blocked by the governor  300 ; as such, there should not be pressurized air being expelled out the secondary nozzles  240 . As the rotational speed increases, the governor  300  is centrifugally deformed. Because the governor  300  is already disposed against the peripheral wall  224  of the chamber  222  for most of its length, the deformation is limited to distention of the governor  300  towards the primary ports  232 , thereby lessening the physical gap between the governor  300  and the primary ports  232  and gradually restricting the flow of pressurized air into the primary nozzles  230 . At some point, the centrifugal force acting on the governor  300  will be balanced by the elastic properties of the governor  300 , and the rotational speed of the impeller assembly  200  will stabilize. Thereafter, when an additional load is applied to the tool  10 , for instance during grinding, the rotational speed of the impeller assembly  200  will drop, thereby lessening the centrifugal force on the governor  300 . With the drop in centrifugal force, the distention of the governor  300  will lessen, thereby opening up the gap at the primary ports  232  and increasing the airflow through the primary nozzles  230 , increasing rotational speed until the forces balance again. Thus, the governor  300  helps control the rotational speed of the impeller assembly  200 , and practically applies an upper limit thereto.  
         [0031]    The secondary nozzles  242  in the impeller body  210  of some embodiments of the present invention provide an independent overspeed safety backup that limits the maximum rotational speed of the impeller assembly  200  separately from the action of governor  300  described above. If the unit is assembled without the governor  300 , or if the governor  300  disintegrates for unknown reasons, then the chamber  222  will operatively communicate with the secondary nozzles  240  via the secondary ports  242 , as the secondary ports  242  are not blocked by the governor  300 . In such a situation, the flow of pressurized air out of chamber  222  would be split between the primary nozzles  230  and the secondary nozzles  240 . Because the primary nozzles  230  and the secondary nozzles  240  are oriented so as to urge the impeller body  210  to rotate in opposite directions, the airflow through the respective nozzles  230 , 240  will counter-act each other, at least to some extent. With the resultant forces in opposition, the maximum rpm of the impeller assembly  200  will be limited, with the maximum rpm of the impeller assembly  200  being less with the secondary ports  242  open than with the secondary ports  242  closed. In this sense, the secondary nozzles  240  may be considered as “retro” nozzles, as they act to retard the runaway rotation of the impeller assembly  200  that might otherwise occur. Accordingly, the presence of the secondary nozzles  240 , normally inactive when the governor  300  is present but active if the governor  300  is missing, provides additional overspeed protection, separate from that provided by the governor  300 .  
         [0032]    The handle portion  40  of the housing  20  is typically rather elongate, with a plastic exterior contoured for easy handling by an operator. The handle portion  40  may mate to the main body  30  via the sleeve assembly  270 , such as by screwing onto the distal threads of the threaded portion  272 . The handle portion  40  may also include a collet  42  or guard on its distal end, as is known in the art. One function of the handle portion  40  is to support the front bearing  280  of the impeller assembly  200 ; thus, the handle portion  40  cooperates with the main body  30  to support the impeller assembly  200  for rotation.  
         [0033]    Some embodiments of the present invention may include a muffling material  150 , disposed within the muffle space  148 , just upstream from the exhaust holes  144 , to aid in quieting the exhaust from the tool  10 . This muffling material  150  may take the form of a felt washer pressed against the underside of the throttle cap  140 , or may take other forms.  
         [0034]    The discussion above has assumed that the hose  12  carried the pressurized motive gas into the turbine tool  10 , but that the exhaust gas was exhausted directly to the ambient environment by the throttle assembly  100 . However, alternate embodiments of the present invention may use what is commonly referred to as an “overhose” arrangement, where the hose  12  also carries away the exhaust gas. For instance, see the embodiment of FIG. 8. In such an arrangement, the cap  140   a  of the throttle assembly  100   a  will still have exhaust holes  144 , but the exhaust holes  144  will be moved radially inward with respect to the throttle cap  140  of FIGS.  2 - 3 . Indeed, the exhaust holes  144  should be very closely spaced with respect to the edge of the embossment  150 . A dual layer hose  12   a  is mated to an overhose adapter  14   a  in a conventional fashion. The adapter  14   a  includes a central hole for the inflowing air, and a plurality of apertures  16  for exhaust air. The apertures  16  are radially spaced similarly to the exhaust holes  144  of the cap  140   a,  so that air exiting the throttle assembly  100   a  will flow into the apertures  16 , through the adapter  14   a,  and then into the outer layer of hose  12   a,  and eventually exhausted from the hose  12   a  appropriately. A suitable seal  15   a,  with an inner diameter greater than the ring of apertures  16  but less than the outer diameter of the adapter  14   a  should be employed to prevent the escape of exhaust from between the cap  140   a  and the adapter  14   a.    
         [0035]    A turbine tool  10  according to the present invention and suitable for operation at approximately 65,000 rpm based on a supply pressure of ninety psig may employ an aluminum impeller body  210  with a roughly square chamber  222  having peripheral walls  224  spaced approximately 0.604 inches apart; with round recesses  228  having a diameter of approximately 0.188 inches and a depth of approximately 0.125 inches (from the top of the peripheral walls  224 ); a shelf depth of approximately 0.050 inches; a buna N governor  300  of 90 durometer (Shore A) with approximately 0.551 inches inner diameter in an undeformed state and a uniform cross-section of approximately 0.070 inches in an undeformed state; and an outer diameter of the manifold  220  of approximately 0.125 inches. Such a turbine tool  10  may have a maximum rpm of approximately 35,000 when the governor  300  is not present in the chamber. The distal end of the spindle  260  of such a turbine tool  10  may be adapted to mate with any appropriate drill bits, rotary files, or the like, in any fashion known in the art.  
         [0036]    While the discussion above has been in terms of using pressurized air as a motive fluid, it should be understood that the present invention also encompasses using any gas, not just air. For example, the motive fluid may be nitrogen or other inert gas if desired.  
         [0037]    The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.