Abstract:
A steering ski for a snowmobile is disclosed. The steering ski comprises a ski body and a wear bar connected to a ski bracket. The ski bracket is used to attach the ski to the balance of the snowmobile. The ski body also receives a reinforcing member that reinforces a portion of the ski body which is curved upwardly. Reinforcing ribs travel along the length of the ski body on an upper portion of the ski body. The sole of the ski body or lower surface includes a keel that expand in width from a forward-most portion and then decreases in width rearward of a juncture between a snow contacting portion of the ski body and the upwardly-extending portion of the ski body. A wear bar is positioned along the keel and depends below a lowermost portion of the keel rearward of the widest portion of the keel. The wear bar extends into the ski body through a forward aperture and a rearward aperture. The rearward aperture is sized and configured to allow ice chips to be passed through the ski body and slung upward to cool various components of the snowmobile.

Description:
PRIORITY INFORMATION 
     This application is based on and claims priority to Japanese Patent Application No. 11-98182, filed Apr. 5, 1999, the entire contents of which is hereby expressly incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to skis for snow vehicles. More particularly, the present invention relates to steering skis having improved tracking and component cooling characteristics for such vehicles. 
     2. Description of the Related Art 
     The use of snowmobiles and similar snow vehicles has increased in popularity in recent years. These vehicles are being used both for utilitarian purposes and for sport and recreational purposes. The vehicles typically are adapted to travel across snow and/or ice and usually include one or more forward facing skis along with a driven belt track or other propulsion mechanism, such as wheels for instance. 
     The sport and recreational use of such snowmobiles is being practiced on groomed trails in ski resort areas, for example. On such surfaces, the snowmobiles are generally easily controlled through the use of weight shifting and steering movement of the skis. However, when the snow becomes packed and/or icy, the snowmobile may be less likely to follow the desired track through the snow. In such instances, the snowmobile may become very difficult to handle. 
     Snowmobile skis typically have an elongated keel that is positioned along the bottom of the ski. The keel acts to increase the bite of the ski in the snow when the ski is turned. Such keels typically leave an impression in the snow corresponding to the profile of the ski and keel. When the snow is wet or compacted, a later following snowmobile ski that happens upon an impression left by a previous snowmobile ski will tend to follow the same track. This condition is generally known as tracking or darting, and is especially prevalent if the temperature has dropped causing wet snow to freeze. Darting forces the snowmobile operator to compensate or correct for the tracking steering forces by oversteering the vehicle to maintain directional stability. This is because the keel of the snowmobile following a track left by a previous snowmobile will naturally situate itself in the previous impression and considerable effort could be required to steer out of such a track. Over time darting can cause the driver to become fatigued from the effort of steering and the handling characteristics of the snowmobile can be greatly decreased. 
     One solution to the darting problem is to simply increase the total width of the keel. The wide keel would promote steerability and decrease the likelihood of a later-following snowmobile from falling within a track left by the more prevalent narrower keeled snowmobile. Such an arrangement, however, suffers from some obvious drawbacks. First, should such a feature become popular, the use of a wider keel would not have the desired effect of reducing darting. Additionally, widening the keel would result in poor turning performance. This is because the ski is often made of a synthetic resin material that is easily elastically deformed. If the keel is increased in width, the keel could deform more readily and the performance of the ski would be impaired and/or compromised. 
     A need therefore exists for an improved steering ski. The ski should be capable of reducing darting while also being capable of long-term usage with minimal maintenance. Preferably, the ski would include a reinforcing runner that would be designed to increase the cutting or carving effect of the ski during turning. Additionally, a forward portion of the runner should extend down below the body of the ski such that the wear bar can increase the cutting or carving ability of the ski when in use. Such an arrangement would result form the reinforcement added by the more rigid wear bar relative to the more flexible ski body. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention involves a ski for a snowmobile comprising a body having a substantially horizontal snow contact section and an upturned forward leading portion. A tip is defined at a forward-most end of the leading portion. The leading portion and the snow-contacting portion meet at a junction. A keel depends downward from the body and the keel increases in width from the tip to the junction and decreases in width rearward of the junction. 
     Another aspect of the present invention involves a snowmobile comprising a body, a pair of skis disposed generally below a forward portion of the body and a drive arrangement disposed generally below a rearward portion of the body. The snowmobile slides on the pair of skis and is powered in at least a forward direction by the drive arrangement. At least one of the skis comprises a passage extending from a lower surface to an upper surface through the ski. The passage is capable of directing ice toward the drive arrangement during forward movement of the snowmobile. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features, aspects and advantages of the present invention will now be described with reference to drawings that show a presently preferred arrangement that is intended to illustrate and not to limit the present invention and in which drawings: 
     FIG. 1 is a side elevation view of a snowmobile having a pair of steering skis having a steering ski arranged and configured in accordance with certain features, aspects and advantages of the present invention; 
     FIG. 2 is an enlarged side elevation view of the steering ski of FIG. 1 having certain internal components illustrated with hidden lines; 
     FIG. 3 is a top plan view of the steering ski of FIG. 1 having a reinforcing gusset and a related mounting assembly illustrated with phantom lines; 
     FIG. 4 is a bottom plan view of the steering ski of FIG. 1 having a wear bar removed therefrom; 
     FIG. 5 is an enlarged cross sectioned side elevation view taken along the line  5 — 5  in FIG. 3 having the reinforcing gusset illustrated with phantom lines and having a portion of the steering ski illustrated with hidden lines; 
     FIG. 6 is an enlarged cross sectioned side elevation view taken along the line  6 — 6  in FIG. 3 having a portion of the steering ski illustrated with hidden lines; and 
     FIGS. 7 a - 7   d  are cross sections through the steering ski taken at various locations along the steering ski as indicated in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference initially to FIG. 1, a snowmobile having a pair of steering skis constructed in accordance with an embodiment of the present invention is identified generally by the reference numeral  10 . While the present invention will be described in the context of a snowmobile, it should be readily appreciated that the present invention also can be used in a variety of other applications, such as all terrain vehicles having at least one front ski, for instance. The snowmobile  10  includes a body assembly  12  made up of a number of parts which may be formed from suitable materials. The illustrated body assembly  12  includes an upper engine shroud  14  and a lower tray  16 , which together define an engine compartment  18 . The engine compartment  18  preferably houses an internal combustion engine  20  for powering the snowmobile  10 . 
     The illustrated body assembly  12  further includes a rear portion  22  that accommodates a seat  24 , which is adapted to seat one or more riders in a straddle fashion. A handlebar assembly  26  is positioned in front of the seat  24  for operation by the rider. 
     The illustrated upper engine shroud  14  includes a raised portion  28  located in front of the handlebar assembly  26 . The raised portion  28  carries a windshield  29  for affording protection to the rider from wind, snow, branches and other objects when operating the snowmobile  10 . 
     A pair of front skis  30 , having a construction to be described, are supported in a manner also to be described at a forward portion of the body  12  with a set of suspension struts  32 . The suspension struts accommodate steering movement of the skis  30 . The struts  32  preferably are interconnected with a tie rod (not shown) so that they can be steered in unison and at least one of the skis  30  preferably has a steering link (not shown) that is connected to a steering rod (not shown). The handlebar assembly  26  is linked to the front skis  30  through the steering rod and a steering column (not shown) such that movement of the handlebar  26  results in a corresponding steering movement of the front skies  30 , as is well known in the art. 
     A carriage assembly  34  is supported at the rear portion of the body  12  below the seat  24  by a rear suspension system  36 . The carriage assembly  34  includes a pair of guide rails  38  that carry a plurality of idler rollers  40 , including a main rear idler roller  42 . 
     The guide rails  38  and idler rollers  40 ,  42  cooperate to form a path around which a drive track  44  is trained. The drive track  44  is driven by an output shaft (not shown) of the engine  20  through a suitable variable belt-type transmission (not shown), as is well known in the art. 
     With reference now to FIG. 2, the illustrated ski  30  generally comprises four components: a ski body  50 , a ski bracket  52 , a reinforcing member  54 , and a wear bar  56 . The ski bracket  52  generally comprises a mounting plate  58 , which is best illustrated in FIG. 5, to which the balance of the ski assembly is attached. The mounting plate  58  extends in a generally longitudinal direction, which is defined as a direction from forward to rear of the snowmobile. The illustrated mounting plate  58  includes a number of apertures or holes through which the ski body  50  and the wear bar  54  are attached to the ski bracket  52 . The illustrated ski bracket  52  also comprises a pair of centrally disposed pivot collars  60 . The pivot collars  60  preferably provide reinforcement at the location to which the ski bracket  52  is attached to the strut  32 . More preferably, the pivot collars  60  also provide a bearing function similar to that provided by a bushing. 
     With continued reference to FIG. 2, the ski bracket  52  desirably is shorter than the overall length of the ski body  50 , and preferably is located in a central region of the ski body  50 . More preferably, the ski bracket  52  is positioned along the ski body  50  such that the portion of the ski body positioned forward of the pivot collars  60  is slightly heavier than the portion of the ski body positioned rearward of the pivot collars  60 . 
     With reference now to FIGS. 2-7, the present ski body  50  will be described in greater detail. Generally speaking, the ski body  50  forms the member upon which the vehicle  10  planes across a ground surface G in a known manner. As illustrated in FIG. 5, the ground G typically is covered by snow and, thus, the ski body  50  has a portion that rides beneath the upper surface of the snow and creates an indentation within the snow in a known manner. The illustrated ski has an overall width that varies with its length. As a general matter, the ski body  50  has an overall width that decreases from front to back. Desirably, a forward portion  62  of the ski body  50 , otherwise known as the approach section, snow contacting portion, of the ski  30 , extends above the upper surface of the snow such that the ski  30  raises above the ground level G during acceleration in a forward direction. In addition, a trailing edge  64  of the ski body  50  also is curved upward away from the ground G such that the vehicle can move rearward without unnecessarily digging the ski  30  into the snow. 
     The ski body  50  is preferably manufactured from a lightweight yet resilient material. In one arrangement, the material is a polyethylene plastic. Of course, any suitable plastic or composite materials can be used. In a presently preferred arrangement, the ski body  50  is manufactured from a material having a density of about 0.93 g/cc and a hardness on the shore D hardness scale of 60 to 62. Preferably, this material has an izod impact strength, double notched, of 80 mJ/mm 2  or above. In addition, the material preferably has a modulus of elasticity of about 530 MPa. Moreover, the material selected preferably should keep over 80% of its properties after ultraviolet testing according to a test method of JIS D205 WAN-IS at 600 hours. One such material is a UHMW polyethylene that is equivalent to Montell IV 26-32 or Ticona IV 26-32. Both of these materials preferably have 0.15% by weight of a UV stabilizer, such as CHPL17. 
     The ski body  50  generally comprises a pair of reinforcing ribs  66  that extend along a length of the upper surface ski body  50 . More particularly, the illustrated reinforcing ribs  66  extend upwardly away from a top surface of a generally planar sole  68  of the ski body  50 . The generally square corners of the sole  68  provide increased cutting action when the snowmobile  10  is sharply turned. Such a feature increases the handling characteristics and maneuverability of the snowmobile. Additionally, at least a portion of the lower surface of the sole  68  includes a pair of outer ridges  69 . The ridges  69  extend downward and improve cornering. Preferably, a keel extends further downward than the outer ridges  69 . 
     With continued reference to FIG. 2, the reinforcing ribs  66  extend from within the upwardly turned forward portion  62  of the ski body  50  and have an increasing height relative to the sole  68  of the ski body  50  and a gradual taper along the length of the ski body  50 . Generally, the height of the reinforcing ribs  66  is maximized just forward of the bracket  52  and just rearward of an attachment location of the reinforcing member  54  in the illustrated arrangement. 
     The reinforcing member  54  is attached to a forward-most portion  70  of the sole  68  as well as to a location just forward of the ski bracket  52 . Preferably, the reinforcing member  54  provides a handgrip  72  that allows an operator to pull the snowmobile  10  by the skis or to manually reposition the skis when the snowmobile  10  is not being operated. The reinforcing member  54  is attached using threaded fasteners, as is generally to those of skill in the art. Preferably, the reinforcing ribs  66  taper toward one another on the forward portion  62  such that they are separated by a gap generally equal to the thickness of the reinforcing member at the forward-most portion  70  ski body  50 . The threaded fastener  74 , which is used to attach the reinforcing member  54  to the ski body  50 , preferably is tightened to a torque of about 8 to 13 Nm. The rearward threaded fastener  76  extends through a tube that is formed as a portion of the reinforcing member  54  and is preferably tightened to a torque of approximately 15 to 18 Nm. Additionally, the reinforcing ribs  66  are joined by a crossing member  78  proximate the location of the threaded fastener  76 . In this manner, the reinforcing member  54  supports the leading portion  62  of the ski body  50 . 
     With reference now to FIGS. 5 and 6, and as explained above, the snow contacts the ski body  50  along the sole  68  at a snow contacting portion  80 . It is on the snow contact portion  80  that the majority of the weight of the snowmobile  10  is carried. More preferably, and as illustrated, the snowmobile  10  planes across the surface of the snow on the snow contact portion, and a portion of snow is compacted underneath the snow contact portion. The forward portion  86  of the ski body  50  that contacts the snow is connected to the leading portion  62  at a junction  82 . Proximate the junction  82  a keel  84  begins to develop. The keel  84  is similar to that used in watercraft that is used to increase the tracking of the snowmobile  10  through the snow and to enable enhanced cornering abilities. More preferably, and as illustrated, the keel actually begins proximate the forward-most portion  70  of the ski body  50 . 
     With reference now to FIG. 4, the keel  84  has a forward portion  86  that begins along the forward-most portion  70  of the ski body  50 . As illustrated, the forward portion  86  of the keel  84  has a narrower width than the widest portion  88  of the keel which is proximate the junction  82  between the snow contacting portion  80  and the forward portion  86  of the keel  84 . As illustrated in FIG. 4, preferably the width of the keel  84  expands as the keel moves rearward from the forward portion  86  until it reaches the junction  82 . Rearward of the junction  82 , preferably the keel  84  decreases in width over its remaining length. The rearmost portion of the keel  94  preferably is narrower than the forward-most portion of the keel  86 . Thus, the keel  84  varies in width along its length. FIGS.  7 ( a )- 7 ( b ) illustrate various sections through the ski  30 . With reference to those figures and FIG. 4, the illustrated keel  84  has a first width  88  proximate the junction  82  and decreases in width in both directions. For instance, the keel  84  has a larger contact surface area in section  7 ( a ) than in section  7 ( b ) and a larger contact surface area in section  7 ( b ) than in section  7 ( c ). Moreover, the contact surface area in section  7 ( c ) is larger than the contact surface area in section  7 ( d ). 
     Moreover, the thickness or depth of the keel  86  preferably increases as along the length of the keel  84  from the forward portion  86 . Just rearward of the junction  82 , the keel has its maximum width or thickness proximate the section b—b  7   b — 7   b  illustrated in FIG. 3, As illustrated in FIG. 7 c , the keel  86  decreases in thickness or depth from the location proximate FIG. 7 b  until it becomes a mere ripple in the lower surface of the sole  68 , as illustrated in FIG. 7 d.  With reference to FIGS.  7 ( a )- 7 ( d ), the illustrated keel  84  has a progression of heights from tallest to shortest as follows: section  7   b — 7   b ; section  7   c — 7   c ; section  7   a — 7   a ; and section  7   d — 7   d.    
     Additionally, the keel  86  includes a pair of raised bosses  90  along at least a portion of its length. Again, these raised bosses  90  decrease in depth or thickness toward a rear portion  92  of the keel  84 . In the illustrated arrangement, the raised portion of the rear portion  94  slowly tapers into the surrounding area of the sole  68  at a location rearward of the rearmost portion  94  of the keel  84 . 
     Desirably, and as best illustrated in FIG.  4  and in FIGS. 7 a-d , the keel  84  has a beveled side edge  96  that extends to both lateral sides of the keel  94  along a substantial portion of the keel. Preferably, the beveled edges  96  begin just rearward of the forward-most portion  86  of the keel  84  and continue even after the rearmost portion  94  of the keel  84 . These tapered edges increase the contact surface area between the ski body  50  and the snow. In addition, these sloping faces  96  improve the handling and maneuverability of the vehicle  10 . Preferably, the slope of the sloping faces  96  is at its minimum proximate the rearmost portion  94  of the keel  84  and again just rearward of the junction  82  in the vicinity of the second hole which will be described below. Thus, the illustrated sloping face  96  has a decreasing slope from the front end of the keel  86  rearward toward the junction  82 . Rearward of the junction  82 , the sloping faces  96  have a slope that first increases toward the rear keel portion  92  and then decreases toward the rear end of the keel  94 . This variable sloping face helps improve the tracking and reduce the darting of the snowmobile  10 . Preferably, the overall dimension of the keel  84 , which includes the outer edge of the sloping faces  96  (i.e., the intersection between the sloping face  96  and the sole  68 ) continues to expand rearward of the maximum width location for the keel  84 . More particularly, in one arrangement, the overall width of the sloping faces and keel  84 ,  96  increases rearward of the junction  82  and then contracts to an overall dimension roughly the same as the width of the keel proximate the junction  82 . The overall dimension then tapers toward the rearmost portion  94  of the keel  84 . 
     As indicated above, the ski  30  also comprises a wear bar  56 . The wear bar generally comprises a host bar  98  and a rigid insert, such as a carbide insert,  100 . With reference now to FIG. 2, it is seen that the host bar  98  extends along a substantial portion of the ski body  50  along its sole  68 . The inserts  100  are positioned proximate a central portion of the host bar  98  in a manner which will be described below. The host bar  98  extends upward through a hole  102  located at the forward-most end of the host bar  98  and also extends upward through a hole  104  located at a rearward-most portion of the host bar  98 . Preferably, and as illustrated in FIG. 2, the forward portion of the host bar  98  is disposed above a lower surface of the ski such that the lower surface protects the forward portion of the host bar  98 . In the illustrated arrangement, the host bar  98  is advantageously recessed within a central portion of the keel  84  between a pair of bosses  90 . The host bar  98  is also provided with a plurality of threaded fastening studs  106 . The studs preferably are connected to the host bar  98  in any suitable manner. In one arrangement, the studs  106  are welded fast to the host bar  98 . In other arrangements, the studs may be integrally formed with the host bar or may be drilled and tapped and connected through to the host bar by a threading engagement. Of course, other mounting arrangements may also be possible. 
     The sole  68 , or ski body  50 , is provided with the forward hole  102  and the rearward hole  104 . As illustrated, the forward hole  102  generally lies beneath the ground plane G while the rearward hole  104  lies above the ground plane G. Such an arrangement results in an advantageous cooling arrangement. More particularly, due to the location, sizing and placement of the rearward hole  104 , ice chips that are encountered as the snowmobile  10  is moved forward through a bed of snow can be urged upward through the opening indicated by the letter I in FIG.  6 . The ice chips being moved upward through this location are expelled upward or shaved upward by the ski  30  and thrown onto components of the drive mechanism requiring cooling. As used herein, ice chips is meant to include snow, snow and ice mixtures and ice as well as melted or melting ice or snow. Thus, the illustrated design results in improved cooling of various features of the drive assembly. 
     The wear bar  56  is attached to the bracket  52  using a resilient mounting. More particularly, the studs  106  that are attached to the host bar  98  of the wear bar  56  are passed upward through holes  108  that are formed in the ski body  50 . The holes are best illustrated in FIGS. 3 and 7 b . As illustrated in FIG. 7 b , the hole  108  is preferably stepped such that it is formed with a counter bore portion. The stepped configuration allows a square headed bolt to be used as the mounting stud  106 . The square headed bolt  106  then is welded to the host bar  98 . Of course, as described above, various mounting arrangements also can be used. 
     The hole  108  also includes a counter bore located on the opposite end of the hole. Thus, a shoulder is located on both ends of the hole  108 . A resilient sleeve or bushing  110  can be positioned within the upper counter bore  112 . The bushing preferably is resilient and is sandwiched between the ski body  50  and the mounting bracket  52 . The resilient member both absorbs shocks and isolates the bracket  52  from at least a portion of the vibrations experienced by the ski body  50 . In one arrangement, the ski body has a total of six (6) apertures  108  through which bolts or studs  106  are passed to connect the wear bar  56  to the ski  30 . In the illustrated arrangement, however, a total of four (4) apertures are used. It should be appreciated, therefore, that any number of apertures can be used so long as the wear bar  56  is properly secured to the ski  30 . 
     In addition, the hole  102  has a teardrop configuration such that the host bar  98  does not have to turn abruptly in order to enter into the hole. Such an arrangement reduces the fatigue on the wear bar during use, as well as uses the manufacturing and assembly as well as the replacement of the wear bars  56 . 
     Similarly, the opening  104  has an elongated teardrop shape. However, the opening  104  also is formed as an elongated slot such that an opening is defined rearward of the portion of the opening  104  filled by the wear bar  56 . As described above, this opening rearward of the wear bar  56  advantageously results in cooling ice chips that are introduced above the plane of the ski  30  and thrown upward into various components requiring cooling. 
     The studs  106  receive a flat washer  114  and a nylon nut, or any other suitable nut,  116 . This mounting arrangement secures the wear bars  56  to the ski  30 . It is anticipated, however, that the wear bar  56  can include apertures that are threaded such that a threaded rod could be extended down into the apertures and tightened in order to fasten the wear bar  56  to the ski  30 . In addition, it should be appreciated that the use of one or more slots rather than the hole  108  would ease an alignment in mounting of the wear bar  56 . Moreover, the ski body  50  preferably includes bosses that substantially surround the holes  108  to reinforce the holes  108 . Such an arrangement is not shown, however, it should be understood by those of ordinary skill in the art to be an advantageous configuration. The nuts should be tightened onto the studs  106  to a torque of approximately 18 to 23 Nm. Such an arrangement ensures the connection while also allowing the nuts to be removed for replacement of the wear bars. More preferably, the forward-most and rearward-most, as well as the innermost two fasteners should be tightened to this degree of torque In arrangements in which there are six fasteners arranged in two groups of three, the intermediate fastener of the forward group, as well as the intermediate fastener of the rearward group, should be tightened to a torque of approximately 8 to 13 Nm. 
     As discussed above, the host bar  98  includes a chip  100 . The chip preferably has a 90° included angle defined at its lowermost edge. This angle can be varied, however, to affect the handling characteristics of the ski  30 . The point defined by the two sloping faces that define the 90° angle is preferably offset from the center of the rod by no more than about about 0.5 mm. More preferably, the chip  100  preferably has a side dimension of 3.2 mm and the chip is a square in cross section. While the diameter of the rod may be approximately 0.4375 inch in diameter, or roughly 11 mm, the total height of the rod and chip combination is approximately 12.8 mm in the preferred arrangement. Moreover, the rod  98  preferably includes a reinforcing weld bead of approximately 0.5 mm on both sides of the chip. The chip  100  preferably extends along approximately 4-10 inches of a central portion of the illustrated host rod  98 . In some arrangements, two or more chips may be aligned end-to-end to form the total chip  100 . In one such arrangement, three chips are arranged end-to-end with the middle chip have a different hardness than the two end chips. Additionally, the two end chips each have an end that is tapered to an angle of about 45°. This tapering provides a knife edge at a forward and rearward portion of the chip  100 . Preferably, the chip is manufactured from carbide or a similar hardened material. The chip  100  desirably is located directly beneath the pivot of the saddle or bracket  52 . In this manner, the chip  100  is most likely to be in contact with the snow surface. As is known, the chip is used to break through or to cut when riding on ice or a similar hardened snow surface. 
     It should also be noted that the wear bar  56  extends downward below the lowermost surface of the ski body  50  including the keel  84  at a location just rearward of the junction location  82 . Such an arrangement improves the tracking of the ski over hardened or compacted snow surfaces. In addition, such an arrangement improves the carving ability of the ski during turning actions of the snowmobile  10 . It should also be noted that the rearmost portion of the wear bar terminates just upward of the lowermost surface of the keel  84 . In other words, the rear portion of the wearbar  56 , which is bent upwardly toward the hole  104 , has a lowermost end that just barely is placed within the hole in the illustrated arrangement. This upward bend reduces the likelihood of damaging the rearward portion of the wear bar  56  while also increasing the ability of the snowmobile  10  to be backed or moved rearward without unnecessary dragging caused by the end of the wear bar  56 . 
     Although this invention has been described in terms of a certain preferred arrangement, other arrangements apparent to those of ordinary skill in the art also are within the scope of this invention. Various changes and modifications may be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is intended to be defined only by the claims that follow.