Patent Publication Number: US-11035417-B2

Title: Boot assembly for a joint member

Description:
REFERENCE TO CO-PENDING APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 15/964,116 filed on Apr. 27, 2018 now U.S. Pat. 10,378,593 issued Aug. 13, 2019. The entire content of this priority application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a boot assembly, such as for a constant velocity joint. 
     BACKGROUND 
     Constant velocity joints (CV joints) are often employed where transmission of a constant velocity rotary motion is desired or required. CV joints are typically greased or otherwise lubricated for the life of the component. The joints are preferably sealed to retain the lubricant inside the joint while keeping contaminants and foreign matter, such as water and dirt, out of the joint. A boot, which may be made of rubber, thermoplastic, silicone material, or the like, usually encloses portions of the CV joints. The boot provides a flexible barrier to retain the grease in the joint and extend the life of the joint. 
     SUMMARY 
     In at least some implementations, a boot assembly for a joint includes a boot made from a flexible material and a boot can. The boot can may include a connecting portion at which the boot and boot can are coupled together, a mounting portion including a flange having a central axis and an inner surface that faces the axis and which extends circumferentially and axially relative to the axis, and a retainer. The retainer is connected to the flange at a first location and is separate from the flange at a second location spaced from the first location so that at least a portion of the retainer is movable relative to the flange. The retainer has a length between the first location and second location and the retainer has an inner surface facing the axis, and the retainer further includes an inward portion spaced from the first location. The inward portion is arranged closer to the axis than is the inner surface of the retainer between the first location and a midpoint between the first location and the second location, and the inner surface of the retainer is not at a constant angle relative to the axis along the length of the retainer. 
     In at least some implementations, the inner surface of the retainer, between the first location and a midpoint between the first location and second location, is not more than 1 mm closer to the axis than a radially innermost portion of the inner surface of the flange separate from the retainer. The inner surface of the retainer, between the first location and a midpoint between the first location and second location, may be at an angle relative to the axis that does not vary by more than 10 degrees. In at least some implementations, the inner surface of the retainer from the midpoint to the first location is parallel to the axis or within 5 degrees of parallel to the axis. The inward portion may be arranged at an angle to the axis of at least 20 degrees. 
     In at least some implementations, the inward portion includes a free end of the retainer that is not connected to and is movable relative to the flange, and the free end may be bent relative to the remainder of the retainer at an angle of at least 20 degrees. The retainer may be coupled to the flange at a base and have a free end that is not connected to and is movable relative to the flange, and is spaced from the base, and the free end may be closer to the axis than is any other portion of the retainer. 
     In at least some implementations, an assembly for a joint includes a joint member having a body with a central axis and an annular mounting surface defined by a portion of a radially outer surface of the body, the mounting surface including a radially inwardly extending void open to the outer surface, and a boot assembly coupled to the joint member. The boot assembly has a boot made from a flexible material and a boot can having a body that includes a connecting portion at which the boot and boot can are coupled together, and a mounting portion received over the mounting surface to couple the boot assembly to the joint member. The mounting portion includes a retainer that is connected to the remainder of the boot can at a first location and is separate from the remainder of the boot can at a second location spaced from the first location, and the retainer is flexible and resilient so that at least a portion of the retainer is movable relative to the remainder of the boot can between an unflexed state and a flexed state. The retainer has a bend spaced from the first location that defines an inward portion of the retainer that, in the unflexed state of the retainer, is located radially closer to the axis than the remainder of the retainer and closer to the axis than at least a portion of the mounting surface. When the mounting portion is received over the mounting surface, the inward portion engages the joint member and the retainer is flexed outwardly to the flexed state wherein the inward portion engages the mounting surface, and when the inward portion is aligned with the void the inward portion may resiliently return toward its unflexed position so that the inward portion is received in the void with part of the inward portion closer to the axis than the mounting surface outboard of the void. Then, removal of the boot assembly from the joint is inhibited by engagement of the retainer with the joint member body. 
     In at least some implementations, the second location includes a free end of the retainer and wherein the inward portion is closer to the free end than the first location. The void may be a circumferentially extending groove, and the boot may include multiple retainers that are circumferentially spaced apart and each arranged for receipt of an inward portion of each retainer in the groove. In at least some implementations, multiple retainers are provided spaced apart about the flange and the mounting surface includes more than one inwardly extending void and the inwardly extending voids are not continuous with each other, are circumferentially spaced around the outer surface, and arranged for receipt of an inward portion of at least one of the retainers. 
     In at least some implementations, the inner surface of the retainer, between the first location and a midpoint between the first location and second location, is not more than 1 mm closer to the axis than a radially innermost portion of the inner surface of the flange. The inner surface of the retainer, between the first location and a midpoint between the first location and second location, may be at an angle relative to the axis that does not vary by more than 10 degrees. The inner surface of the retainer from the midpoint to the first location may be parallel to the axis or within 5 degrees of parallel to the axis. 
     In at least some implementations, the inward portion is defined in a free end of the retainer that is movable relative to the flange and the free end is bent relative to the remainder of the retainer at an angle of at least 20°. The inner surface of the retainer is not at a constant angle relative to the axis along the length of the retainer. 
     In at least some implementations, a constant velocity joint includes an outer race, an inner race, multiple balls positioned between the inner race and outer race to transmit torque between the inner race and outer race, a boot and a boot can. The outer race has a central axis, an axial end and an outer surface including a radially inwardly extending void open to the outer surface and spaced from the axial end. The boot can is coupled to the boot and to the outer race, and has a mounting portion received over the axial end of the outer race. The mounting portion includes an inner surface that faces the axis and extends axially relative to the axis from an axial end of the boot can and the mounting portion includes a retainer. The retainer has a base that is connected to the boot can within the mounting portion and the retainer having a movable end that is spaced from the base and not connected to the boot can. The retainer is flexible about the base relative to the flange so that the retainer can flex between an unflexed state and a flexed state. And the retainer has a bend spaced from the base that defines an inward portion of the retainer that, in the unflexed state of the retainer, is located radially closer to the axis than the remainder of the retainer and closer to the axis than a portion of the outer surface of the outer race. At least a portion of the retainer is received within the void with the inward portion closer to the axis than at least a portion of the outer surface of the outer race and removal of the boot assembly from the joint is inhibited by engagement of the retainer with the outer race. 
     In at least some implementations, the inner surface of the retainer is not at a constant angle relative to the axis along the length of the retainer. The inward portion may be located closer to the movable end than the base. And at least a portion of the retainer is radially overlapped by the outer race once the retainer is received within the void. 
     Various features and components may be combined together except where they are mutually exclusive, in accordance with the description below, which is intended to illustrate the various features rather than limit the inventions described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of preferred implementations and best mode will be set forth with regard to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a CV joint with a boot of a boot assembly removed; 
         FIG. 2  is a cross sectional view of the CV joint including the boot assembly; 
         FIG. 3  is an exploded sectional view of the CV joint; 
         FIG. 4  is a partial sectional view of the boot can and an outer race of the CV joint to which the boot can is coupled; 
         FIG. 5  is an enlarged partial sectional view showing a retainer of the boot can in a void of the outer race; 
         FIG. 6  is a sectional view similar to  FIG. 5  showing the boot can prior to assembly on the outer race; and 
         FIG. 7  is an enlarged sectional view of the boot can showing the retainer. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in more detail to the drawings,  FIGS. 1-3  illustrate a constant velocity (CV) joint  10  that allows for transmission of constant velocities at angles typically encountered in every day driving of automotive vehicles. The CV joint  10  may be used, for example, with half shafts, interconnecting shafts and propeller shafts of these vehicles, or otherwise as desired. The CV joint  10  may have an outer race  12  and an inner race  14  pivotally coupled to one another and arranged to define multiple ball tracks for carrying a plurality of torque transmitting member, like rollers or balls  16  so that the inner race and outer race co-rotate. The CV joint  10  may be any type of constant velocity joint, such as a tripod, double offset, cross-groove, Rzeppa, and the like. And as set forth herein, a boot assembly  18  may be coupled to the CV joint. 
     The outer race  12  has a central axis  20  about which the outer race rotates, and an inner surface  22  with multiple outer ball tracks defined in the inner surface. To facilitate coupling the boot assembly  18  to the outer race  12 , the outer race may include in an outer surface  24  a radially inwardly extending void  26  open to the outer surface and axially spaced from a first axial end  28  of the outer race  12 . As shown in  FIG. 3 , the outer race  12  may contain an axially inwardly extending gland or groove  29  open to the first axial end  28  and radially spaced from the central axis  20 , and a gasket or seal  31 , such as an o-ring may be received within the groove  29 . A mounting surface  30  to which the boot assembly  18  is mounted is defined between the axial end  28  and at least the void  26 . The mounting surface  30  may be annular and extend circumferentially around the outer race  12 . In one embodiment this void  26  may be a continuous groove or channel that extends around the circumference of the outer race  12 , although the void  26  may include multiple discrete voids spaced circumferentially around the outer surface  24  of the outer race  12 , if desired. The void(s)  26  include a radially inner surface  27  that is closer to the axis  20  (e.g. has a smaller diameter) than is the outer surface  24  of the outer race  12 . The outer race  12  is generally made of metal, such as steel, however, any other type of metal material, plastic, or composite material, etc., may also be used for the outer race in at least some implementations. 
     The inner race  14  may be received at least partially within (e.g. axially overlapped by) the outer race  12  and may have an outer surface  32  in which multiple inner ball tracks are defined. The inner ball tracks in the inner race  14  are aligned with the outer ball tracks in the outer race  12  and the balls  16  are positioned between the inner race and outer race with each ball received within a respective one of the outer ball tracks and inner ball tracks. The inner race  14  may be made of steel, however, any other metal composite, hard plastic, etc., may also be used. 
     To help retain the balls  16  between the outer race  12  and inner race  14 , a cage  34  with openings in which the balls are located is received between the outer and inner race. The cage  34  may be annular, at least partially axially overlapped by the outer race  12  and the inner race  14  (i.e. radially between the races), and may be made of a steel material but other metal materials, plastics, composites, etc. may also be used. 
     In at least some implementations, a first shaft or rotary component  36  ( FIGS. 1-3 ) is coupled to the inner race  14  and a second shaft or rotary component  38  ( FIG. 2 ) is coupled to the outer race. The balls  16  permit pivoting of the inner race relative to the outer race and thus, pivoting of the first rotary component  36  relative to the second rotary component  38  while the rotary components rotate together, at the same rotational velocity. 
     On or at a second axial end  42  of the CV joint  10 , a grease cap  40  may be fitted to the outer race  12  for retaining grease or other suitable lubricant within the CV joint  10  and inhibiting contaminants from entering the joint. Grease cap  40  may also contain a venting mechanism  41 , represented in  FIGS. 2-3  as a vent valve, that allows for high pressure gas to be expelled during joint operation. Opposite to the grease cap  40 , the boot assembly  18  may enclose at least part of the CV joint  10  to retain grease within the joint and inhibit entry of contaminants into the joint. 
     In at least some implementations, the boot assembly  18  includes a boot can  44  and a flexible boot  46 . The boot can  44  may be annular, have a central axis (which may be coaxial with the outer race) and first and second axially spaced ends  48 ,  50 . The boot can  44  may be formed of a substantially rigid material, such as but not limited to, aluminum, steel, carbon fiber and composite. The flexible boot  46  may be constructed of a flexible material, such as, but not limited to, rubber based products, plastics, urethane, silicones, elastomers, silicone, thermoplastic elastomer (TPE), and any other flexible composite materials. It is understood however, that boot  46  may comprise any other suitable material that is sufficiently flexible to allow the CV joint  10  to operate through a wide range of angles. 
     The flexible boot  46  and the boot can  44  are coupled together at a connecting portion  52  of the boot can  44  which may include the first axial end  48  of the boot can and may be located radially outwardly spaced from the first rotary component  36  to provide clearance between the rotary component, the boot can and at least a portion of the boot. In assembly of the CV joint  10 , the boot  46  may be coupled to the first rotary component  36  (e.g. by a connector, like a clamp or band) at a location spaced from the connecting portion  52 , and may include a pleat or bellows  54  between the portion of the boot coupled to the first rotary component and the portion of the boot coupled to the boot can  44  at the connecting portion. In this way, the boot  46  may accommodate pivoting of the first rotary component  36  relative to the boot can  44 . 
     The boot can  44  may be coupled to the outer race  12  opposite the grease cap  40 . In this regard, the boot can  44  may have a body with a mounting portion  56  that may include a flange  58  extending to the second axial end  50  of the boot can. The flange  58  may be circumferentially continuous and may have an inner surface  60  that faces the axis  20  and extends circumferentially and axially relative to the axis. The inner surface  60  of the flange  58  may be sized and arranged to be received over a portion of the outer surface  24  of the outer race  12 . Between the connecting portion  52  and the mounting portion  56 , the boot can  44  may include an intermediate portion  61  ( FIGS. 2 and 3 ) which may extend at a non-zero angle relative to the axis  20 , and is shown as being perpendicular to the axis  20  and overlying at least part of the first axial end  28  of the outer race  12 . The intermediate portion  61  may engage and seal against the axial end  28  and/or the seal  31  in the axial end. Instead of the seal being carried by the outer race, the seal could be carried by (e.g. molded onto or coupled to) the boot can in the intermediate portion  61 . 
     To facilitate coupling the boot can  44  to the outer race  12 , the flange  58  or other portion of the boot can  44  may include at least one retainer  62 . Alternate embodiments are possible that do not require a flange  58  or that the retainers  62  be on a flange. In at least some implementations, the retainer  62  is connected to the flange  58  at at least one first location  63  and separate from the flange  58  at at least one second location  65  spaced from the first location so that a portion of the retainer  62  is movable or bendable relative to the flange  58 . In at least some implementations, this may be accomplished by the retainer  62  being cantilevered to the boot can  44 , as depicted in  FIG. 3 , with a void  64  surrounding a portion of the retainer and defining a free end  66  that may move relative to the flange  58  and a base (e.g. the first location  63 ) fixed to the flange and defining a living hinge about which the retainer may bend or flex relative to the flange. However, other variations are possible. For example, by way of a non-limiting example, it is possible to have sides or other portions of the retainer  62  partially connected to the flange  58  by a coupler which may include a portion of the boot can  44  itself or another material or component. In at least some implementations, a plurality of retainers  62  are carried by (e.g. coupled to) the flange  58  and are circumferentially spaced apart about the flange. In at least some implementations, the first location  63  is closer to the second axial end  50  of the boot can  44  than is the second location  65 , and hence, the free end  66  is farther from the axial end  50  than is the base  63  of the retainer  62 . The flange  58  and retainer  62  may or may not be continuous with one another and may or may not be made of the same material. The flange  58  may be made of the same material as the rest of the can  44  or may be made of another suitable material. The retainer(s)  62  may be made of an at least somewhat flexible and resilient material to permit the retainers to be flexed during installation of the boot can  44  and to return to or toward their unflexed position or state in an assembled position, as set forth in more detail below. 
     As shown in  FIGS. 4-7 , the retainer  62  has an inner surface  68  that faces the axis  20 . This inner surface  68  of the retainer  62  is not at a constant angle relative to the axis  20  along the axial length of the retainer  62 . That is, the inner surface  68  is not linear along the axial length of the retainer  62 . In at least some implementations, the retainer  62  includes an inward portion  70  that extends radially inwardly toward the axis  20  at a different angle than a portion of the retainer  62  between the inward portion  70  and the first location or base  63 . The inward portion  70  may be defined by or include a transition or bend  72  at which the angle of the retainer  62  relative to the axis  20  changes. At least part of the inward portion  70  defines a radially innermost portion of the retainer  62 . That is, part of the inward portion  70  is closer to the axis  20  than is the remainder of the retainer and/or the inner surface  60  of the flange  58 . In implementations including multiple retainers  62 , the inward portion  70  of the multiple retainers may collectively define a smallest inner diameter or dimension of the flange  58 . The inner diameter or dimension defined by the inward portions  70  of the retainers  62  may be less than an outer diameter of at least a portion of the outer race  12  between the axial end of the outer race  12  and the void  26  in the outer race. 
     The inward portion  70  or bend  72  can be located at various points along the length of the retainer  62  between the first location  63  and the second location  65 . In at least some implementations, the bend  72  is spaced from the base  63  of the retainer and is within a portion of the retainer  62  between the base  63  and the free end  66 . The bend  72  and/or inward portion  70  may be closer to the free end  66  than the base  63 , if desired. In other words, the inward portion  70  may begin between a midpoint of the axial length of the retainer  62  (e.g. a midpoint between the base  63  and free end  66  in the illustrated example) and the second or free end  66  of the retainer  62 , and may extend to and include the free end  66 . The retainers  62  may be similarly constructed and arranged, may be axially aligned (that is, at the same axial distance from an axial end  50  of the boot can  44 ), and the inward portions  70  may extend to the same distance from the axis  20 , with provision for normal part tolerances. In some implementations, the bend  72  is positioned with respect to the first location  63  at a ratio not less than 2.75 to 1. That is the linear portion of the retainer  62  between the first location  63  or base and the bend  72  is at least 2.75 times the length of the non-linear portion of the retainer  62  between the bend and the second location  65  or free end  66 . That is, the bent section of the retainer  62  is shorter than the straight section of the retainer  62 , with the straight section of the retainer being at least 2.75 times longer in length than the bent section in at least some implementations. 
     As shown in  FIG. 7 , prior to assembling the boot can  44  to the outer race  12 , the retainers  62  are in an unflexed position or state. To assemble the boot can  44  to the outer race  12 , the second axial end  50  of the boot can  44  is slid over the first axial end  28  of the outer race  12  in a first direction. To facilitate aligning the boot can  44  with the outer race  12  and initially sliding the boot can over the outer race, the second axial end  50  of the boot can  44  may include a radially outwardly flared lip  74  having an inner surface that is radially farther from the axis  20  than is the inner surface  68  of the retainer  62 . Also or instead, the axial end  28  of the outer race  12  may be radially tapered (e.g. as shown in  FIGS. 5-7 ) so that the axial end  28  has a smaller outer diameter than does a portion  76  ( FIGS. 5 and 6 ) spaced from the axial end. 
     As shown in  FIG. 6 , when the boot can  44  is slid onto the outer race  12 , the base  63  of the retainers  62  are passed over the first axial end  28  of the outer race  12  before the inward portions  70 . Until the inward portions  70  are passed over the outer race  12 , in at least some implementations, the retainers  62  are minimally or not at all flexed by any engagement with the outer race. When the boot can  44  is slid onto the outer race  12  far enough, the inward portions  70  engage the outer race (e.g. at portion  76 ) and the retainers  62  are initially flexed outwardly (defining a flexed state of the retainers). The retainers  62  remain in the flexed state until the boot can  44  is slid onto the outer race  12  far enough that the inward portions  70  are aligned with the void  26 . Then, the resilient retainers  62  return to or toward their unflexed state and the inward portion  70  is received within the void  26  as shown in  FIGS. 2, 4 and 5 , and may engage or be adjacent to the inner surface  27  of the void  26 . In implementations with discrete, spaced apart voids  26 , the retainers  62  may each be received in a void aligned with each respective retainer. In this position, the inward portions  70  of the retainer  62  are radially overlapped by the outer race  12  outboard of the void  26  to inhibit or prevent unintended removal of the boot can  44  from the outer race in a second direction opposite to the first direction. That is, forces tending to move the boot can  44  in the second direction are resisted by engagement of the retainers  62  with the outer race  12  from within the void  26 . 
     The nonlinear retainers  62  permit better control over the point of engagement between the retainers and the outer race  12  during assembly of the boot can  44  to the outer race. In at least some implementations, the point of engagement of the outer race  12  with the retainers  62  is axially away from the base  63  of the retainers so that the force or stress of the engagement and flexing of the retainer is spread across a longer axial length of the retainer than if the retainer were to engage the outer race closer to the base of the retainer. 
     Spreading out the stress along a greater length of the retainer  62  reduces the maximum stress generated in the retainer and may limit or prevent plastic deformation of the retainer to ensure that the retainer can resiliently return to or toward the unflexed state when aligned with the void  26  in the assembled position of the boot can  44 . Due to tolerances in the manufacture of the boot can  44  and the outer race  12 , to ensure that the retainer(s)  62  engage(s) the outer race and may be received in the void  26  to retain the boot can on the outer race, a portion of the retainer(s), in at least some implementations are radially closer to the axis  20  than the outer surface  24  of the outer race  12  by up to and including 1.5 mm. With a retainer  62  that is arranged at a constant angle to the axis  20  along its axial length, and due to variances on the sizes of the boot can  44  and outer race  12  in production runs of these components, some of the retainers may be engaged by the outer race undesirably close to the base of the retainers which may cause plastic deformation of the retainers. 
     With the inward portion  70  of the retainers  62  described herein being arranged at a greater angle to the axis  20 , the location of engagement can be controlled to be at or near the inward portion  70  and not near the base  63 , to better distribute the bending/flexing stress along a greater length of the retainer. That is, the portion of the retainer  62  between the base  63  and a midpoint of the retainer  62  can be arranged to not engage the outer surface  24  of the outer race  12 , or to minimally engage the outer surface  24  with the range of tolerances for the boot can  44  and outer race  12 . Engagement of the retainers  62  with the outer race  12  can still be ensured by providing the inward portion  70  at a suitable distance from the axis  20  to ensure engagement of the inward portion with the outer race. Still further, in at least some implementations, the inward portions  70  include a convex outer surface portion due to the inward bend  72  of the retainer  62  to form the inward portion. The convex outer surface portion may be arranged to engage the outer race  12  within the void  26  (that is, engage a sidewall  78  of the void) as shown in  FIG. 5 , and such engagement may tend to bend the retainer inwardly, toward the axis  20 . This inhibits unintended outward flexing of the retainer  62  which could tend to remove the inward portion  70  of the retainer from the void  26 . In this way, forces tending to move the boot can  44  in the second direction may tend to flex the inward portions  70  further inwardly and thereby increase the retention of the boot can to the outer race  12 . 
     In at least some implementations, the retainer  62  may be arranged relative to the flange  58  and outer race  12  so that, between the base  63  and a midpoint of the retainer between the base and free end  66 , the retainer does not significantly engage the outer surface  24  of the outer race  12 . In this example, significant engagement is an engagement that would cause flexing or bending of the retainer  62  by more than 10 degrees relative to the axis  20  of the boot can  44 . Lower stress engagement may be permitted, that is, engagement that causes minimal flexing of the retainer  62  due to engagement between the base  63  and midpoint of the retainer with the outer race  12 . In at least some implementations, the inner surface  68  of the retainer  62  between the first location or base  63  and the midpoint (represented by line  80  in  FIG. 7 ) has an angle relative to the axis  20  that does not vary by more than ten degrees and this portion of the retainer  62  may have an inner surface at a distance from the axis  20  equal to or greater than the greatest radial distance of the outer surface  24  of the outer race  12  between the axial end  28  of the outer race and the void  26 . In at least some implementations, the inner surface  68  of the retainer  62  form the midpoint to the first location  63  is parallel to the axis  20  or within five degrees of being parallel to the axis. In another embodiment, the inner surface  68  of the retainer  62  between the first location  63  and a midpoint between the first location  32  and second location  65  (e.g. between the base  63  and the free end  66 ) is not closer than 1 mm to the axis  20  than is a radially innermost portion of the inner surface  60  of the flange  58  outboard of a retainer  62 . In another embodiment, the inward portion  70  of the retainer  62  may be defined in or otherwise include the free end  66  of the retainer  62 . In yet another embodiment the retainer  62  from the bend  72  to the free end  66  (represented by line  82  through a midpoint of the retainer radial thickness) is arranged at an angle of at least twenty degrees relative to the axis  20 , as shown in  FIG. 7 . 
     In some implementations, the retainers  62  also better maintain the compressive force on the seal  31  between the boot can  44  and the outer race  12  and may maintain direct contact between the boot can  44  and the first axial end  28  of the outer race  12 . In at least some implementations, the axial distance between an inner surface of the intermediate portion  61  of the boot can  44  and free end  66  of the retainers  62  is less than the axial distance between: 1) an axially outward facing portion of the seal  31  that protrudes from the first axial end  28  of the outer race  12 ; and 2) the sidewall  78  of the void or groove  26  adjacent to the free end  66  of the retainer  62  in assembly. Thus, some compressive force may be maintained on the seal  31 . 
     While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention. 
     All terms used in the claims are intended to be given their broadest reasonable construction and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.