Abstract:
An elastomeric track assembly and track band having damping features is disclosed. The track comprises several surfaces disposed as to dampen the force of impact. The track is configured to have a ground contacting surface and portion not in contact with the ground. The idler and road wheels where applicable are disposed above a portion of the track that is not primarily in contact with the ground surface in order to prevent alignment between the wheel and the point of impact with the ground surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present patent application claims the benefits of priority of U.S. Provisional Patent Application No. 62/067,020, entitled “Elastomeric track assembly and track band having damping features”, and filed at the United States Trademark and Patent Office on Oct. 22, 2014, the content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to an elastomeric track that is installed on traction assemblies used as wheel replacements for wheeled vehicles. More particularly, the present invention relates to an elastomeric track that comprises damping capabilities allowing the absorption of force coming from the ground or the impact of the track on the ground. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many recreational vehicles such as snowmobiles and ATVs are provided with track systems for propelling them. 
         [0004]    In the case of a snowmobile, the track system forms an integral part of the vehicle and the track system is fully integrated in the overall construction and suspension of the vehicle. 
         [0005]    In the case of an ATV (including UTV or SSV), the track systems are often used in replacement of the wheels normally used for propelling the vehicle. 
         [0006]    Still, on an ATV, the track system is configured to support and drive an endless track typically, but not necessarily, made from elastomeric material. Hence, the vast majority of track systems comprise at least one drive wheel (e.g. a sprocket wheel), a more or less complex support structure, at least one idler wheel and road wheel. 
         [0007]    Generally, in these traction systems, the weight of an ATV is transferred to the track by the road wheels of the traction assembly. Typically the load needs to be transferred to the ground as quickly as possible while stress in the track needs also to be reduced as much as possible to enhance the lifetime of the track. For these reasons, tracks are designed to have profiles located directly under the contacting wheels areas. In such configuration, the load of the wheel applied on the track is directly transferred to the ground through the outer profiles located directly under the contacting wheel areas and in contact with the ground (vertical alignment of the wheels and outer profiles in contact with the ground.) 
         [0008]    ATV are often used and operated in off-road environments where they encounter hard and/or immovable obstacles such as rocks, roots, etc. When the track systems of these vehicles encounter such obstacles, they must overcome them. However, overcoming hard and/or immovable obstacles generally involves shocks and other vibrations that are transmitted to the vehicle and ultimately to its operator. 
         [0009]    More particularly on an ATV, the impacts can also results in an involuntary reaction in the steering, depending on the type of obstacles and the area where they touch the tracks. 
         [0010]    Having outer profiles positioned directly under the contacting wheels areas does not provide any improvement to such scenario. Indeed, as it transmits the load in the opposite direction, it also transmits the shocks and vibrations. 
         [0011]    In the past, many attempts to reduce the transmission of vibration and shocks to the vehicles and its operator have been tried. For instance, in U.S. Patent Application Publication No. 2012/0242141, a track system for use as a wheel replacement on a wheeled vehicle is disclosed. In this track system, the support structure comprises a suspension which allows the track system to absorb some shocks and vibrations. 
         [0012]    Still, most past attempts to reduce the transmission of vibrations and shocks to the vehicle and its operator imply bulky or otherwise complex arrangements that add costs and complexity to the track system. Furthermore, these systems do not overcome involuntary reactions in the steering as a result of impact on obstacles or other objects. Hence, there is a need for a track system that can mitigate at least some of the aforementioned shortcomings. 
       SUMMARY OF THE INVENTION 
       [0013]    Accordingly, one aspect of the present invention the endless track is made of elastomeric materials that generally do not have profiles touching the ground directly under the wheels of the track system where the track is installed and when the load is applied to the track. 
         [0014]    The track of the present invention are in general, but not necessarily, installed on a traction assembly. This traction assembly generally comprises a sprocket wheel which is adapted to be mounted to the vehicle, preferably on the wheel hub thereof. The traction assembly also generally comprises a support structure which preferably, but not necessarily, supports idlers wheels and/or road wheels. The track of the present invention is generally, but not necessarily, disposed around and cooperates with the sprocket wheel, the support structure and, if any, the idler and/or road wheels. 
         [0015]    The endless track of the present invention comprises an inner wheel-engaging surface and an outer ground-engaging surface. The inner wheel engaging surface comprises at least two longitudinally extending areas where the wheels will engage the track. The outer ground-engaging surface, which is provided with a plurality of traction lug profiles, further defines at least three laterally extending portions extending along the circumference of the track that can be separated in two groups: laterally extending portions in contact with the ground on hard surface, and laterally extending portions not in contact with the ground on hard surface. In accordance with the present invention, the wheel engaging areas (more particularly, the center of the wheel) are located in the laterally extending portions not in contact with the ground on a hard surface when the load is applied on the track. 
         [0016]    Consequently, when a vehicle equipped with a traction assembly equipped with a track of the present invention is ridden over a hard surface such as, but not limited to, concrete or pavement, only laterally extending portions with higher traction lugs of the endless track will effectively engage the ground. On this type of surface, a track with the contacting wheel areas aligned with a laterally extending portion with lower tractions lugs not in contact with the ground can&#39;t directly transfer the load to the ground. To go there the ground, the load transmitted by the wheels needs to travel laterally in the track to reach a portion where there are traction lugs in contact with the ground. 
         [0017]    According to one aspect of the present invention, the load by being overhanged by laterally extending portions with higher traction lugs out of the wheel contacting area, similar to a cantilever beam, generally creates a deformation in the track. In addition to this deformation, the load is away from the ground in a vertical way. 
         [0018]    According to one aspect of the present invention, the mechanism of the track system is similar to that of a complete suspension system. In a typical suspension, an ATV for example, the wheel is the item in contact with the ground and the load is the ATV itself. As for the track in accordance with the principle of the present invention, the load is not vertically aligned with the point of contact to the ground. As such the load has to travel laterally to reach that point. The suspension is the laterally element that allow the load to be transmit to the wheels. The specific configuration of the track of the present invention plays that role. Also, by not having the load and the point of contact to the ground aligned, the inertia needs to be considered. All these features and configuration works together as a damper/shock absorber when the track hits an obstacle. 
         [0019]    When looking at an ATV hitting an obstacle, more likely a wheel of the ATV, we can see the wheel going up much higher than the ATV frame. This effect is caused by the suspension between the wheel and the ATV frame, in other words, the point of contact to the ground and the load. When hitting an obstacle, the inertia of the ATV (load) wants to keep the ATV at his original height, but oppositely, the wheel that hits the obstacle needs to go up. To reduce the opposite effect of both components, the suspension absorb the impact before it reach the ATV, to allow the inertia to keep the ATV at is position. 
         [0020]    The endless track of the present invention works the same way. When the track hits an obstacle, laterally extending portions of the lug profiles with higher traction lugs are more likely to be the one hitting the obstacle and going up. The road wheels of the ATV conversion system carries the load, so much more inertia forces the ATV to stay at its original position. In this case, the track needs to play the role of the suspension to allow both elements to work together. A feature of the present invention is to not have a profile under the wheels in a way that allows the hitting point to be located vertically under the wheel. Having an impact vertically in alignment with the wheels will result in no damping effect due to the direct transfer of the impact to the wheel of the track assembly. Consequently, one aspect of the present invention is a track band, also referred as an endless track, wherein the lug profile under the wheel contact area is different from the ground impacting area as to require the force of impact to be directed through the track as to have a damping effect, thus reducing the force of impact transferred to the wheels, and to the ATV. 
         [0021]    According to another aspect of the present invention, when a vehicle having the disclosed track assembly and track band is ridden over a soft surface, such as, but not limited to, snow, mud or sand, all the traction lugs of the track will generally engage the ground since the higher traction lugs will at least partially penetrate the soft surface, thereby allowing the smaller traction lugs to also engage the ground. In this situation, no or very little traction and/or flotation will be lost because every profiles and the total width of the track will be in contact with the ground. 
         [0022]    According to another aspect of the present invention, the track is mounted on a traction assembly comprising a sprocket wheel which is adapted to be mounted to the vehicle, preferably on the wheel hub thereof, a support structure which preferably, but not necessarily, supports idlers wheels and/or road wheels, the track being disposed around and cooperates with the sprocket wheel, the support structure and, if any, the idler and/or road wheels, the endless track comprising an inner wheel-engaging surface and an outer ground-engaging surface, the inner wheel engaging surface comprises at least two longitudinally extending areas where the wheels will engage the track, the outer ground-engaging surface, which is provided with a plurality of traction lug profiles, further defines at least three laterally extending portions extending along the circumference of the track that can be separated in two groups: laterally extending portions in contact with the ground on hard ground, and laterally extending portions not normally in contact with the ground on hard ground wherein the center of the wheel engaging areas are located in laterally extending portions not normally in contact with the ground on hard surface when the load is applied on the track. 
         [0023]    According to one aspect of the present invention, the track band may be reinforced with stiffening rods. 
         [0024]    According to one aspect of the present invention, the track band may comprise openings in the track used for driving the track. 
         [0025]    According to one aspect of the present invention, the track band driving lugs are used to drive the track. 
         [0026]    According to one aspect of the present invention, the center of the wheel engaging areas of the track system is aligned with the center of the wheel. 
         [0027]    According to one aspect of the present invention, at least 50% of the wheel engaging area is located in laterally extending portions not normally in contact with the ground on hard surface. According to another aspect of the present invention the wheel engaging areas have a width up to twice the width of the wheel. 
         [0028]    In one aspect of the present invention, it is provided an endless track for a track assembly, the track assembly comprising a supporting frame, a sprocket wheel pivotally mounted to the supporting frame, idler wheels pivotally mounted to the supporting frame, and road wheels pivotally mounted to the supporting frame. The endless track further comprises an inner wheel-engaging surface and an outer ground-engaging surface. The outer ground-engaging surface comprises traction lugs located along a circumference of the endless track defining a central portion and at least two lateral portions, wherein an average thickness of the lateral portions is inferior to an average thickness of the central portion, and wherein at least half of a wheel contacting area is in contact with the inner wheel-engaging surface corresponding to the lateral portions whereby rigidity of the lateral portions allows a damping effect. 
         [0029]    The endless track may further comprise widthwise reinforcing stiffeners. 
         [0030]    The sprocket wheel may further comprise teeth and the endless track may further comprise apertures to be engaged by the said teeth. 
         [0031]    In another aspect of the invention, the wheel contacting area may be fully in contact with the inner wheel-engaging surface corresponding to the lateral portions. In a further aspect of the invention, thin and flexible traction lugs may be connected to the lateral portions. 
         [0032]    Furthermore, the widthwise center of the inner wheel-engaging surface may be aligned with the widthwise center of the wheels. 
         [0033]    In further aspects of the invention, the thickness of the lateral portions may be variable along a transversal direction of the endless track or the variation of the thickness of the lateral portions may be linear. 
         [0034]    In further aspects of the invention, the thickness of the central portion may be variable along a transversal direction of the endless track or the central portion may be punctual in a lateral direction. 
         [0035]    In yet another aspect of the present invention, the inner wheel-engaging surface may comprise lugs adapted for engaging the driving wheel and for guiding the road and idler wheels. 
         [0036]    The invention is further directed to a method of manufacturing an endless track as defined herein above. 
         [0037]    The invention is also further directed to a vehicle equipped with a plurality of endless tracks as defined herein above. 
         [0038]    The invention is yet further directed to an endless track for a track assembly, the track assembly comprising a supporting frame, a sprocket wheel pivotally mounted to the supporting frame, idler wheels pivotally mounted to the supporting frame, and road wheels pivotally mounted to the supporting frame. The endless track comprises an inner wheel-engaging surface, an outer ground-engaging surface, and widthwise reinforcing stiffeners. The outer ground-engaging surface comprises traction lugs located along a circumference of the endless track defining a central portion and at least two lateral portions, shape of the lateral portions being different than shape of the central portion, and wherein at least half of a wheel contacting area is in contact with the inner wheel-engaging surface corresponding to the lateral portions whereby a rigidity of the lateral portions allows a damping effect. 
         [0039]    The invention is also yet further directed to a vehicle equipped with a plurality of endless tracks as defined herein above. 
         [0040]    Other and further aspects and advantages of the present invention will be obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]    The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which: 
           [0042]      FIG. 1  is a side view of a traction assembly for an ATV where the track in accordance with the present invention can be used. 
           [0043]      FIG. 2  is a side view of a track in accordance with the present invention. 
           [0044]      FIG. 3  is a bottom view of a track in accordance with the present invention. 
           [0045]      FIG. 4  is a top view of a track in accordance with the present invention. 
           [0046]      FIG. 5  is a front cross-sectional view of a track with support wheels, in accordance with the present invention. 
           [0047]      FIG. 6  is a comparison between a typically ATV suspension and the track of the present invention. 
           [0048]      FIG. 7  is a front cross-sectional view of a prior art track with support wheels. 
           [0049]      FIG. 8  is a top view of another track in accordance with the present invention. 
           [0050]      FIG. 9  is a side view of another track in accordance with the present invention. 
           [0051]      FIG. 10  is a front cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
           [0052]      FIG. 11  is a front partial cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
           [0053]      FIG. 12  is a front partial cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
           [0054]      FIG. 13  is a front partial cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
           [0055]      FIG. 14  is a front partial cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
           [0056]      FIG. 15  is a schematic view of the shape of the cross section of another embodiment of a track band to illustrate the ground contacts. 
           [0057]      FIG. 16  is a schematic view of the shape of the cross section of another embodiment of a track band to illustrate the ground contacts. 
           [0058]      FIG. 17  is a top view of another track in accordance with the present invention. 
           [0059]      FIG. 18  is a front partial cross-sectional view of a track with support wheels, in accordance with the present invention (another possible configuration). 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0060]    A novel elastomeric track with damping features will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby. 
         [0061]    Now referring to  FIG. 1 , in the present embodiment, it is shown a traction assembly  100 , where a track system can be installed, generally comprising a sprocket wheel  110  adapted to be fixedly mounted to the wheel hub or axle which is generally operationally connected to the suspension and/or steering system of a vehicle (not shown). The traction assembly  100  also comprises a supporting frame structure  120  to which idler wheels  130  and road wheels  140  are preferably mounted. The idlers wheels  130  are preferably respectively mounted at the fore and at the aft of the supporting frame  120  while the road wheels  140  are generally mounted along the frame  120 , between the front and rear idler wheels  130 . The track assembly has a longitudinally extending endless track  150  preferably made from reinforced elastomeric material disposed around the sprocket wheel  110 , the idler wheels  130 , the road wheels  140 , and the supporting frame  120 . 
         [0062]    Referring now to  FIGS. 2, 3 and 4 , in the present embodiment, the endless track  150  generally defines an inner wheel-engaging surface  160  and an outer ground-engaging surface  170 . The inner wheel-engaging surface  160  is preferably provided with guide lugs  161  and  163  which are adapted to guide the endless track  150  and to prevent lateral movement thereof. The endless track  150  may be provided with a least one row of longitudinally aligned holes  162  adapted to be engaged by the sprocket wheel  110 . 
         [0063]    Understandably, the present configuration should only be viewed as one of many possible configurations. 
         [0064]    Still referring to  FIGS. 2, 3 and 4 , the ground-engaging surface  170  is provided with a plurality of generally laterally extending tractions lug profiles  171  and  172  which are disposed along the circumference of the track  150 . Other possible configurations are shown on  FIGS. 8 and 9 . 
         [0065]    Now referring to  FIG. 5 , the endless track  150  of the present invention comprises an inner wheel-engaging surface  160  and an outer ground-engaging surface  170 . The inner wheel engaging surface comprises at least two longitudinally extending areas  164  where the road wheels  140  will generally engage the track  150 . The outer ground-engaging surface  170 , which is provided with a plurality of traction lug profiles  171 , further defines at least three laterally extending portions  173 ,  174 ,  175  extending along the circumference of the track. The laterally extending portions can be separate in 2 groups: laterally extending portions in contact with the ground— 176 —on hard surfaces, and laterally extending portions not in contact with the ground— 177 —on hard surfaces. In accordance with the present invention, center of the wheel engaging areas  164  is located in laterally extending portions  177  not in contact with the ground. 
         [0066]    Now referring to  FIG. 6  in the present embodiment, the track  150  can be compare to a suspension of an ATV. The ATV suspension system typically comprise the ATV  10 , the wheel  20  and the suspension  30 , which further comprise the suspension arms  31  and the damper  32 . 
         [0067]    Still referring to  FIG. 6 , according to the present embodiment, the load  11  of the ATV  10  is not aligned with the point of contact  21  on the ground  1 . The track  150  of the present embodiment has features similar to the features required to create a suspension system. As such, the load  11  is transmitted by the wheel  140 . Consequently, the profiles  171  are in contact with the ground  1  while the load  11  and point of contact  21  on the ground  1  are not aligned. Between these two points, the area  34  is the equivalent of the suspension  30  of a typical suspension system and the track portion  33  is the equivalent of the damper  32 . 
         [0068]    Consequently, an ATV equipped with a traction assembly  100  having the track of the present embodiment  150 , when encountering an obstacle on or off the road, will react in a way similar to a suspension system. As such, the portion  176  will generally be the portion hitting the obstacle. The impact will then be transmitted to the wheel  140  while passing through the damping area  34  thus reducing the amount of force transmitted to the vehicle. 
         [0069]    Now referring to  FIG. 7  illustrating a prior art endless track  150  having similar features as the track of the present embodiment but lacking the damping effect. In such prior art embodiment, the centers of the wheel engaging areas  164  are not aligned with the laterally extending areas  177  which correspond to the areas typically not in contact with the ground on hard surface. The wheel engaging areas are thus located in the laterally extending areas in contact  176  with the ground on such hard surfaces. As a result of this type of configuration, the impact transmitted to the wheel  140  resulting from an impact with an obstacle on the ground has a direct way to the wheel  140  and is not required to travel laterally in the track to reach the ground. Therefore, the damping effect of the track  150  according to the present embodiment typically generated by the overhanging of the load compare with the ground contacting area, is not present in the prior art endless track configuration. 
         [0070]    Now referring to  FIG. 10 , in this other embodiment, another configuration of the endless track  150  of the present invention is shown. In this embodiment, the laterally extending areas  174  and  175  are flat instead of being at an angle. The centers of the wheel engaging areas are still in the laterally extending areas  177 , thus not in contact with the ground on hard surfaces. 
         [0071]    Now referring to  FIG. 11  in yet another embodiment of the present invention, another configuration of the endless track  150  is shown. In this embodiment, the laterally extending areas  174  and  175  are flat instead of being at an angle and 4 wheels  140  are engaging the track in the wheel engaging areas  164 . The centers of the wheel engaging areas  164  are still in the laterally extending areas  177 , thus not in contact with the ground on hard surfaces. 
         [0072]    Now referring to  FIG. 12  in yet another embodiment of the present invention, another configuration of the endless track  150  is shown. In this embodiment, four wheels  140  are engaging the track  150  in the wheel engaging areas  164 . The centers of the wheel engaging areas  164  are still in the laterally extending areas  177 , thus also not in contact with the ground on hard surfaces. 
         [0073]    Now referring to  FIG. 13  in yet another embodiment of the present invention another configuration of the endless track  150  is shown. In this embodiment, four wheels  140  are engaging the track in the wheel engaging areas  164 . There are 7 laterally extending areas  174 ,  174 A,  173 ,  173 A,  173 B,  175 ,  175 A that can also be divided in 2 groups: laterally extending portions in contact with the ground— 176 —on hard surfaces, and laterally extending portions not in contact with the ground— 177 —on hard surfaces. The centers of the wheel engaging areas  164  are still in the laterally extending areas  177 , thus not in contact with the ground on hard surfaces. 
         [0074]    Now referring to  FIG. 14  in yet another embodiment of the present invention another configuration of the endless track  150  in accordance with the present invention is shown. In this embodiment, there are five laterally extending areas  174 ,  173 ,  173 A,  173 B,  175  than can also be divided in two groups: laterally extending portions in contact with the ground— 176 —on hard surface, and laterally extending portions not in contact with the ground— 177 —on hard surface. The centers of the wheel engaging areas  164  are still in the laterally extending areas  177  not in contact with the ground on hard surface. 
         [0075]    Now referring to  FIGS. 15 and 16 , according to one embodiment of the present invention, the track has a profile  150  allowing a lateral offset of the force of impact from directly underneath the idler and road wheels. The profile  150  should have a shape that avoids continuous contact with the ground on hard surfaces directly underneath the wheels. In  FIGS. 15 and 16 , the cross sectional shapes of the tracks  150  are an arc of a circle and a v-shape, respectively as to allow single punctual contact  324  with the ground  322  on hard surfaces. In these types of cases, no ground contact is generally allowed directly on the sections  210  in alignment with the bottom portion of the wheels  140 . As such, these track profiles  150  will, upon impact, require the force of impact to laterally travel through the track  150 , thus having a damping effect before being directed to the wheel and ultimately to the small vehicle structure itself. 
         [0076]    Now referring to  FIGS. 17 and 18 , in this other embodiment, another configuration of the endless track  150  of the present invention is shown. In this embodiment, the laterally extending areas  174  and  175  are flat instead of being at an angle. Laterally extending areas  174  and  175  are thin and flexible in order to not transfer the load between the ground and wheels. The centers of the wheel engaging areas are still in the laterally extending areas  177 , thus do not support the wheels on hard surfaces. 
         [0077]    While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.