Patent Publication Number: US-7219711-B2

Title: Hydraulic door opening mechanism and method of installing a bi-fold door

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/537,570 filed on Jan. 20, 2004 and U.S. Provisional Application No. 60/589,754 filed on Jul. 21, 2004, hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a hydraulic door opening/closing mechanism for use with an overhead bi-fold door and a method of manufacturing and installing the same. 
     BACKGROUND OF THE INVENTION 
     Bi-fold doors have long been used wherever high clearance is needed in a doorway. Bi-fold doors are commonly used in agricultural, industrial, and aviation settings in lieu of the more common track mounted overhead door, as the bi-fold door does not require the same headroom as does the track mounted overhead door, the track mounting system being unnecessary for the bi-fold door. 
     Opening mechanisms for prior art bi-fold doors commonly use electric motors as the source of the forces needed to open the door. However, electric motors are somewhat limited in their output, the larger motors being somewhat heavy for the application. In addition, it is difficult to operate an electric motor in at varying speeds without losing a significant portion of the power output of the motor. Finally, electric motors are relatively slow in that the amount of torque that they put out allows the typical bi-fold door to be opened only in a steady state, slow manner. 
     It has been found, however, that a small, self-contained hydraulic door opening mechanism may be used in place of the standard electric motor to overcome the problems inherent in electric motors under such conditions. 
     It is an objective of the present invention to adapt a hydraulic motor and/or cylinder to open and close a bi-fold door. It is a further object of the present invention to provide a door opening mechanism that can quickly and quietly open a bi-fold door and also actuate automatic locking systems incorporated into the door. It is yet another object of the present invention to simplify the installation of a bi-fold door by pre-assembling the door with its door opening mechanism at the time of manufacture, leaving only the task of mounting the door on its hinges in the door opening and connecting electric power to the door opening mechanism. A final object of the present invention is to provide a hydraulically operated door opening mechanism that may be controlled through a hard-wired control circuit or wirelessly using a suitable transmitter and receiver. 
     These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a prior art overhead door with the door in its fully open position. 
         FIG. 2  shows a cross sectional view of the prior art overhead door of  FIG. 1  according to section line  2 - 2  of  FIG. 1  and includes a phantom view of the door in a partially open condition. 
         FIG. 3  shows a cross sectional view of the prior art overhead door of  FIG. 1  according to section line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a fragmentary, front elevation view of the left side of the prior art overhead door in its closed condition. 
         FIG. 5  is a schematic, front elevation view of a hydraulic door opening mechanism of the present invention including a hydraulic motor. 
         FIG. 6  is a schematic, front elevation view of a hydraulic door opening mechanism of the present invention including a hydraulic cylinder. 
         FIG. 7  is a front elevation of an embodiment of the hydraulic door opening mechanism of  FIG. 5 . 
         FIG. 8  is a side elevation of the embodiment of the hydraulic door opening mechanism of  FIG. 7 . 
         FIG. 9  is a schematic, front elevation view of an embodiment of a hydraulic door opening mechanism that includes a hydraulic door locking mechanism. 
     
    
    
     All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood. 
     Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “upper,” “lower,” “first,” “second,” “inside,” “outside,” and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention. 
     DETAILED DESCRIPTION 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention, which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     An overhead door constructed according to the teachings of the preferred embodiment of the present invention is shown in the drawings and generally designated by reference numeral  10 . Door  10  is utilized for opening and closing a doorway  12  or other desired opening in a building or the like. Generally doorway  12  includes a horizontal header  14  and first and second vertical doorjambs  16  located on opposite ends of header  14 . 
     Door  10  includes an upper door panel  18  and a lower door panel  20 . Upper door panel  18  is hingedly mounted about a horizontal axis adjacent its upper edge  22  to header  14  by hinges  24 . The horizontal axis of hinges  24  is located on header  14  at a spaced relation from doorway  12 , and in one embodiment hinges  24  are located in the range of about nine inches from the top of doorway  12 . Lower door panel  20  is hingedly mounted about a horizontal axis to the upper door panel  18  by pivot(s)  26  or by an equivalent hinge structure. A pivot  26  generally includes a pivot plate  28  that extends from the inside surface of upper door panel  18  adjacent to its bottom edge  30  and a pivot plate  32  that extend from the inside surface of the lower door panel  20  adjacent to its upper edge  34 . A pivot pin  36  extends through and pivotally connects pivot plates  28  and  32  to one another to form a pivot  26 . 
     Door  10  is generally moveable between a first, closed position where door panels  18  and  20  are vertically aligned to close doorway  12  and a second, open position where door panels  18  and  20  are generally horizontal and substantially parallel to each other. In some embodiments, the respective door panels may be of different widths. However, panels  18  and  20  both rest against doorjambs  16  around doorway  12  of the building when in its first, closed position. 
     Door  10  may include mechanisms for supporting the door  10  in its open position. Support mechanisms such as first and second brace members  38  have first ends  40  pivotally mounted to the side edges  42  of upper door panel  18  about a horizontal axis by pivot pins  44 . In a preferred form, pins  44  are spaced apart from the bottom edge  30  of upper door panel  18 . Also, brace members  38  may advantageously have a length greater than the height of lower door panel  20  and so extend to a height generally equal to the height of pins  44  above the bottom of doorway  12  when door  10  is in its closed position as shown in  FIG. 4 . Thus, in one particular embodiment, the second or lower ends  46  of brace members  38  may generally be even with the bottom end  48  of the lower door panel  20  when door  10  is in its closed position. Brace members  38  may further include rollers  50  at their second ends  46  for purposes to be explained further hereinafter. 
     Door  10  further includes rollers  64  located on opposite side channel beams  66  of lower door panel  20  adjacent its bottom end  48 . Rollers  50  and  64  of brace members  38  and panel  20  roll along the outside surface of doorjambs  16 , which may include suitable track members  17  to movable guide rollers  50  and  64 . 
     Door  10 , according to the teachings of the present invention, further includes flaccid members  70  shown in the most preferred form as cables extending between lower door panel  20  and brace members  38  adjacent the bottom edge of panel  20  and ends  46  of brace members  38 . 
     The basic construction of door  10  according to the preferred teachings of the present invention having been set forth, the operation of door  10  will now be described. In operation, in its closed position, brace members  38  abut vertically with doorjambs  16  of door  12 . When raising means  52  is activated thereby winding cable  60  on winch  54 , bottom end  48  of panel  20  is vertically drawn upward by cable  60 . Due to pivot  26  and hinges  24 , door panels  18  and  20  begin to fold. As door  10  is thus raised upwardly, rollers  64  of panel  20  roll along doorjambs  16 , and particularly along tracks  17  in the preferred embodiment. Door panels  18  and  20  are thus supported by hinges  24 , pivot  26 , and rollers  64 . Brace members  38  do not initially provide support to door  10 , and as is shown in phantom lines in  FIG. 2 , rollers  50  on braces  38  do not engage doorjambs  16  when door  10  is partially raised. As bottom end  48  of panel  20  is drawn upwardly, cables  70  become tight such that brace members  38  are raised with door panel  20 . When door panel  20  is located adjacent to its open position, rollers  50  of brace members  38  engage with doorjambs  16  and tracks  17  thereon. As door  10  continues to move to its open position, brace members  38  support the bottom edge  30  of top door panel  18  to keep door panels  18  and  20  from tipping into doorway  12 . When door  10  is in its open position, rollers  64  of door panel  20  do not have to engage the doorjambs  16 . 
     When door  10  is moved from its open position to its closed position, cable  60  is unwound from winch  54  lowering bottom edge  48  of panel  20 . Rollers  50  of brace members  38  then roll down the doorjambs  16  until rollers  64  engage with doorjambs  16  and support door  10 . At that time, cables  70  hold brace members  38  adjacent to door panel  20  until door  10  is adjacent its closed position. In its fully closed position, brace members  38  abut against doorjambs  16  and lie against the building face. The narrower width of lower door panel  20  with respect to upper door panel  18  permits brace members  38  to be pivotally supported outside of side channel beams  66  of lower door panel  20  closely adjacent thereto and still lie against and be guided within tracks  17 . Since brace members  38  have a length greater than the height of lower door panel  20 , they are able to engage doorjambs  16  at an acute angle thereto as shown in  FIG. 2  to properly support the outer or lower end  30  of upper door panel  18  with door  10  in its open position. 
     It can thus be appreciated that brace members  38  provide an angular support between the bottom edge  30  of upper door panel  18  and the doorjambs  16  to prevent the door panels  18  and  20  from pivoting downwardly as a unit about hinges  24  into doorway  12  when door  10  is raised to the fully open position of  FIG. 2 . Specifically, prior to the present invention, the bottom door panel was not typically moved into a parallel relation with the top door panel but angled downwardly and inwardly towards the building frame with a typical vertical header space of about two feet to serve as a support mechanism for the top panel. Thus, the overhead room with the door  10  in its open position was decreased and/or the total height of the door was increased to compensate for this triangular positioning of the door panels. Thus, utilizing brace members  38  according to the teachings of the present invention allows the door panels  18  and  20  to be positioned horizontally to each other while providing the support necessary to prevent the folded door from tipping into the doorway. In its preferred form, the vertical header space for door  10  according to the present invention is generally equal to the distance of hinges  24  from the top of doorway  12  and in the preferred embodiment is generally in the range of nine inches. Due to the horizontal positioning of door panels  18  and  20 , the overhead space at doorway  12  is increased while minimizing door panel size according to the teachings of the present invention. 
     It should be further appreciated that lower door panel  20  is very securely held in the open position by cable  60  extending between the bottom end  48  of panel  20  and upper edge  22  of panel  18 , and by its connection at pivot  26  to upper door panel  18 . 
     Additionally, pivot plates  28  and  32 , which position pivot pins  36  inwardly from edges  30  and  34  of door panels  18  and  20 , allow door panels  18  and  20  to be horizontal in the open position of door  10 . Specifically, if the pivotal connection between the door panels were located adjacent to their abutting edges, it would be necessary for the door panels to abut with each in order to be parallel to each other, a physical impossibility for many hinges. Furthermore, if the door panels are not in a horizontal position, the lower door panel then is angled downwardly and inwardly into the doorway, decreasing overhead room and resulting in other disadvantages as set forth hereinbefore. 
     It should be appreciated that the mounting of power means  52  adjacent to lower edge  48  of door panel  20  is advantageous over other mounting positions. Specifically, motor  56  and winch member  54  can be easily mounted to door panel  20  when door  10  is in its closed position without requiring the heavy lifting and positioning required when the motor and winch are mounted above the doorway  12 . Furthermore, the weight of motor  56  and winch member  54  on door  10  acts as an anchor in providing dead weight thereto when door  10  is in its closed position to provide stability to door  10 . 
       FIG. 5  schematically illustrates a door raising mechanism  100  according to one embodiment of the present invention. The mechanism  100  includes a hydraulic pump  102  that is operatively coupled to a hydraulic fluid reservoir  104 . The pump  102  operates on known principals to maintain a predetermined operative hydraulic pressure at all times. Pump  102  is electrically coupled to a power source by connector  106 . 
     Pump  102  is coupled to hydraulic motor  108  by means of valve manifold  110  that controls the flow of pressurized fluid through hydraulic lines  112 ,  114 . Note that hydraulic lines  112 ,  114  are illustrated schematically and in the various embodiments of the present invention provide for a complete fluidic circuit that allows hydraulic fluid to flow from the reservoir  104 , through pump  102  and manifold  110  to motor  108  and then back again to reservoir  104 . Manifold  110  is operated remotely by control  116 , shown in  FIG. 5  mounted to the wall adjacent the door opening in which door  10  is mounted. 
     When so directed by control  116 , manifold  110  permits pressurized fluid to pass from pump  102  through hydraulic lines  112 ,  114  to hydraulic motor  108 . Rotary power generated by the motor  108  is transmitted through coupling  118  to shaft  120 . Shaft  120  has mounted thereon one or more take-up spools  122  that act to raise or lower the door panels  18 ,  20  as previously described as cable  60  is wound up or off of the spool  122 . An additional take-up spool  124  may be mounted on the shaft  120  to activate a door lock  126  such as that shown in  FIGS. 7 and 8 . Take-up spool  124  may have a cable  61  wound thereon. 
     The mechanism  100  for opening and closing the door  10  is mounted directly upon the door  10 . While the mechanism  100  can be mounted on the door  10  during installation of the door  10  in a door opening, it is preferred to mount the mechanism of the door  10  at the time of manufacture and prior to the door&#39;s installation in opening  12 . 
     The mechanism  100  is preferably mounted on the door  10  near the bottom edge of lower panel  20 . The weight of the mechanism  100  acts to keep the door closed. In another embodiment, the mechanism  100  can be mounted on the upper door panel  18  to reduce the amount of weight that must be lifted and supported. A door can include one or more mechanisms  100 , and can have any useful ratio of motors  108  to pumps  102 , reservoirs  104  or manifolds  108 . By way of example only, a single, properly sized reservoir  104  may be coupled to multiple hydraulic motors  102  through a single manifold  110  or through multiple manifolds  110 , all of which is coupled to control  116 . 
     The manifold  110  includes the necessary fluid flow valving to effect the flow of pressurized fluids needed to activate the motor  108 . The manifold  110  allows for selective control of the opening and closing of the door  10  and can raise or lower the door at various speeds and over varying distances. Where the door  10  is provided with two motors  108  to raise and lower the door  10 , the motors  108  can be controlled jointly or independently of one another. Independent control of motor  108  allows for precise closure and opening of the door  10  and can obviate the need for manually adjusting the door opening and closing mechanism  100 . The travel of the door  10  between its open position and closed position can be managed automatically by positioning sensors that detect the position of the door and control the manifold and motors accordingly. Alternatively, the position of the door  10  can be controlled mechanically by its placement of mechanical stops that actuate the manifold  110  mechanically or through control  116  so as to stop the motor  108 . 
     The control  116  may be hardwired directly to manifold  110  as by connector  111  or may be coupled remotely thereto as by radio signal or similar communicating means. As can be appreciated, the control  116  may be hardwired directly to the manifold  110  by connector  111  while additional controllers (not shown) are wirelessly connected to manifold  110 . 
     The motor  108  may be connected directly inline with shaft  120  as shown in  FIG. 5  or may be connected through a transmission  119  (see  FIG. 7 ) that allows for misalignment of the motor  108  and shaft  120 . Similarly, resilient couplers may be used as shown at  118  to accommodate slight misalignment and to cushion the application of torque from the motor  108  to shaft  120 . Preferably, the motor  108  will be operated so as to quickly open and close the door  10  without applying high impulse forces to the shaft  120  is such a way as to damage the various components of the door  10  or mechanism  100 . Note that because of the power and control available from the application of hydraulic power to the door opener, the door  10  may be opened and closed at variable rates, some of which are much faster than that of an electric door opener. Accordingly, it is possible to open and close a bi-fold door  10  at numerous rates that may be faster, slower, or discontinuous with respect to the rates at which an electric door opener can operate. In some applications, particularly in smaller applications of the type used in standard garages and in small airplane hangars, it is possible that a bi-fold door  10  may be opened and closed in a time of about 8-10 seconds, a time that is generally faster than that of a door having an electric door opener/closer. It is also to be understood that multiple opening mechanisms  100  may be mounted on a door  10 . This is particularly useful where the door  10  has a large height and/or width. 
     The motor  108 , manifold  110 , or pump  102  will preferably be provided with an external or internal brake (not shown) of a mechanical or hydraulic nature that will prevent the rapid closure of the door  10  should power to the mechanism  100  be suddenly lost. 
     An alternate embodiment of a hydraulic door opening mechanism is illustrated in  FIG. 6 . This door opening/closing mechanism is schematically identified as  200  in  FIG. 6 . Door opening mechanism  200  includes a reservoir  204  that is coupled to a pump  202 . The pump  202  is in turn coupled to a manifold  206  by hydraulic line  210 . Manifold  206  is coupled by hydraulic line  212  to a hydraulic cylinder  208 . Note that hydraulic lines  210  and  212  are illustrated schematically in  FIG. 6  and in practice provides a complete hydraulic circuit that permits hydraulic fluid to flow from the reservoir  204 , through pump  202  and manifold  206  to cylinder  208  and back again. Cylinder  208  is secured at a base end  214  to door  10 . 
     Manifold  206  is controlled by controller  216  and may be hard wired directly to the controller as by connector  218  or controlled wirelessly by a suitable transmitted/receiver mechanism(s). Pump  202  is also provided with power through power conduit  203 . 
     Hydraulic cylinder  208  has a rod  220  that is moveable between an extended position (seen in  FIG. 6 ) and a retracted position. A distal end  222  of rod  220  has affixed thereto a pulley(s)  224  that is opposed by pulley(s)  226 . Pulley(s)  226  is secured to door  10  such that pulley  224  moves relative to pulley  226  as rod  220  moves between its extended and retroacted positions. 
     One or more cables  228  are wound about pulleys  224 ,  226  such that the linear motion of rod  220  is multiplied. Cables  228  are in turn coupled to cables  230  that act to raise and lower the door  10 . Cables  230  are passed around traveler pulleys  231  to that direct the cables  230  into an appropriate position to open and close the door  10 . The relationship between the linear motion of the rod  220  and that of cables  230  may be controlled by specifying the appropriate pulley diameters. As can be appreciated, the travel of its rod  220  must be sufficient to fully open and close the door  10 . Note that multiple mechanisms  200  may be provided to open and close the door  10 . 
     A door  10 , complete with opening/closing mechanism  100  or  200  may be manufactured and installed as follows. The dimensions of a door opening are obtained and the door  10  and its panels  18  and  20  are sized accordingly. The respective door panels  18 ,  20  are then hinged to one another. Once the panels  18 ,  20  of the door  10  are secured to one another, the pump  102 , reservoir  104 , manifold  110 , motor  108  or cylinder  208 , and associated hydraulic lines  112 ,  114  are secured to the frame of the door  10  in their operative positions. Shaft  120  and spools  122 ,  124  are next mounted in their operative positions on the door  10 . Where the door  10  is provided with a cylinder  208 , pulleys  224 ,  226 , and  231  are mounted in their desired positions and cables  228  and  230  are installed. At this stage, the door  10  is functionally complete and needs only to be secure within the door opening. Once the door  10  is hung in its opening, connector  106  is coupled to a power source (not shown) and control  116  is mounted. 
     A door latch mechanism  350  is shown in  FIG. 9  in a first, closed position in which the door latch mechanism  350  has secured a lower panel  20  of the bi-fold door  10  to its jamb  16 . Door latch mechanism  350  is adapted to work in conjunction with a door opening/closing mechanism  100  or  200  such as those illustrated in  FIGS. 5 and 6 . The hydraulic power units of the door opening/closing mechanisms  100  and  200 , consisting of a reservoir  102 ,  104 , a pump  104 ,  204 , and a manifold  110 ,  206 , may be readily adapted to actuate disparate types of door latch mechanisms  350 . By way of example only, the hydraulic mechanisms of door opening/closing mechanisms  100  or  200  of the present invention may be used to actuate door latch mechanisms such as those described in U.S. Pat. Nos. 4,609,027, 5,343,923, 5,168,914, and 6,547,292, all of which are commonly assigned herewith and incorporated by reference herein. An exemplary embodiment of door latch  126  of a type that may be actuated by a door opening/closing mechanism  100  or  200  is seen in  FIGS. 7 and 8 . 
     In one embodiment, an actuating mechanism  400  for actuating a door latch mechanism  350  includes a hydraulic cylinder  402  having a reciprocable piston  404  slidably received therein. A base  406  of cylinder  402  is coupled to the lower panel  20  of the door  10 . A distal end  408  of the piston  404  has a pulley  412  coupled therein. A cable  410  is passed around pulley  412  and extends laterally from the hydraulic mechanism  400  around a number of additional pulleys  414  and  416  to the door latch mechanism(s)  350 . Where so desired, a resilient member (not shown) may be coupled between the piston  404  and the pulley  412  or between the cylinder  402  and the base  406  to ensure that a desirable minimum amount of tension is applied to the cable  410 . 
     The door latch mechanism  350  may be actuated between an open position in which the door  10  may open and close and a closed or locked position in which the door latch mechanism  350  secures the door  10  to its jamb  16  by means of cylinder  402 . Where the door  10  is in its fully closed position as shown and it is desired to secure the door  10  to its jamb  16 , the manifold  110  supplies pressurized fluid from the pump  102  to the cylinder  402  such that the piston  404  is retracted. The retraction of piston  404  tensions cable  410  and moves the door latch mechanism  350  into its closed or locked position. Conversely, the manifold  110  may supply to, or release, pressurized fluid from the cylinder  402  so as to extend the piston  404 , thereby releasing the door latch mechanism  350  to move back to its open position, shown in phantom lines. When the door latch mechanism  350  is in its open position, the door  10  is free to open and close. 
     Note that where a single door latch mechanism  350  is used, the end of the cable  410  not attached to the door latch mechanism  350  will be secured to the door panel  20  or directly to the piston  404 . Where two door latch mechanisms  350  are used, the door latch mechanisms  350  will be coupled to the piston  404  by pulleys  412 ,  414 ,  416  as shown and described. In one embodiment, the hydraulic mechanism  400  may utilize a rotary actuator that winds cable  410  up on a drum (not shown) to actuate the door latch mechanism  350 . 
     In another embodiment, a cylinder  402  may be secured directly between the door latch mechanism  350  and the door panel  18  or  20  to which the door latch mechanism  350  is secured. In this manner, the cylinder  402  may directly reciprocate or operate the door latch mechanism  350  between the latch mechanism&#39;s open and closed positions. 
     It is also to be understood that multiple hydraulic mechanisms  400  may be provided to actuate the door latch mechanism  350 . By way of example only, where the door latch mechanism  350  is spring biased to return to its open position when an actuating force placed upon the mechanism  350  is released, a one way or single acting actuator or cylinder may be used, the single acting actuator applying and releasing an actuating force on the door latch mechanism  350  rather than actively actuating the door latch mechanism  350  between its open and closed positions. A double acting hydraulic actuator may be used to actively actuate the door latch mechanism between its open and closed positions where the door latch mechanism  350  is not resiliently biased towards its open position. Alternatively, multiple single acting actuators may be employed, each actuator performing a single, predetermined function. For example, a first single acting actuator may be used to open the door latch mechanism  350  and a second single acting actuator may be used to open the door latch mechanism  350 . 
     Note that in operation, the hydraulic actuation mechanism  400  will work in conjunction with a door opening mechanism  100  to automatically open/close and unlock/lock the door  10 . As can be readily appreciated, the door latch mechanism  350  must be opened/unlocked before the door  10  can be opened. Accordingly, the door latch mechanism will be actuated to its open position before the door  10  is opened. At the very least, the controls for the door  10  and door latch mechanism  350  (preferably combined as at  116 ) will ensure that the door  10  may not be opened without first determining that the door latch mechanism  350  is in its open position. Similarly, the controls  116  will be constructed and arranged such that the door latch mechanism  350  will not be actuated unless the door  10  is in its closed position. The arrangement of the controls  116  that enables the correct and safe operation of the hydraulic actuator  400  and door latch mechanism  350  may be microprocessor controlled and/or determined by the status/position of a plurality of position/limit switches (not shown). 
     Thus, since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.