Patent Publication Number: US-7591332-B1

Title: Integrated heat exchanger and engine mount for a snowmobile

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   The present application is a divisional of U.S. application Ser. No. 11/066,833, filed Feb. 24, 2005, which is expressly incorporated by reference herein. 

   BACKGROUND AND SUMMARY OF THE INVENTION 
   Certain embodiments of the present invention relate to heat exchangers in engine cooling systems. Some embodiments of the present invention relate to such heat exchangers that provide a rigid base against which an engine may be mounted. 
   Snowmobiles are popular land vehicles used as transportation vehicles or as recreational vehicles in cold and snowy conditions. In general, a snowmobile has a central frame or chassis on or around which the various components of the snowmobile are assembled. Typical snowmobiles include skis for steering, a seat, handlebars, and an endless track for propulsion mounted to a central chassis. A bulkhead is defined by a plurality of front structural members of the chassis. The engine drives a ground-engaging endless track disposed in a longitudinally extending drive tunnel formed within the chassis. The skis serve to facilitate steering as well as to provide flotation of the front of the snowmobile over the snow in which it is operated. The skis are mounted at the front body portion of the chassis. A handlebar assembly, positioned forward of the seat, is operatively linked to the skis for steering the snowmobile. The skis may be pivoted laterally to steer the snowmobile, for example, by turning the handlebars. 
   Past snowmobiles have used liquid cooling systems to cool their internal combustion engines. Snowmobiles with these liquid-cooled engines often have heat exchangers spaced away from the engine itself. In some of these snowmobiles, the heat exchangers are positioned within the drive tunnel that is within the snowmobile chassis. The drive track, also disposed within the drive tunnel, carries and circulates snow within the drive tunnel as the track moves. The heat exchangers are positioned adjacent the track so that some of the snow carried by the track will be thrown at the heat exchangers to provide a heat transfer. The melting of snow requires a substantial amount of heat that is removed from the coolant circulated in the heat exchangers. 
   Typically a snowmobile with a liquid cooled engine has one of the cooling system elements placed in the front close off area of the chassis. The reason for this is that it is one of the most effective cooling area of the snowmobile due to the snow and ice that is thrown into this area from the drive track. The cooler is typically mounted to the front close off panel. On the opposite side of the close off panel typically there are some structures that are designed to receive motor mounts for isolating the engine vibration from the chassis. 
   It is also desirable to isolate engine vibrations from the chassis. When snowmobiles are powered by two-stroke engines, large amounts of vibration are often produced. In order to decrease the amount of vibration from the engine to the chassis, typically, engines are supported by an engine mount attached to the bottom of the engine in a way that enabled vibration absorbing elements to be placed between the engine mount and the chassis. However, such conventional engine mounts require relatively large amounts of space within the chassis for the engine and to provide the space needed to position the vibration absorbing elements. 
   Also, the tunnel and bulkhead have traditionally been made of a very strong but light-weight material such as aluminum. To withstand the forces encountered under normal operating conditions, reinforcing elements are added to increase the rigidity of the tunnel and bulkhead so that they do not bend or buckle under high loads. Unfortunately, this adds significantly to the overall weight of the vehicle. 
   As engines increase in size and weight, less space is available for within the chassis for mounting such larger and heavier engines. In addition, the chassis must be reinforced to support a heavier engine. Yet, additional reinforcements require additional chassis space. Accordingly, there exists a need for a new engine mount that can be used in a snowmobile that occupies less space, is more easily assembled and is more lightweight. Similarly, there is a need for a new front heat exchanger having such desirable properties where the chassis has less available space for both the engine and for such an new engine mount. 
   Certain embodiments of the invention relate to a snowmobile with a chassis, an engine, a heat exchanger, and an engine mounting assembly. The heat exchanger includes a reinforced portion that supports the engine. The heat exchanger also is mounted to the chassis, contains an inner passage for carrying heat absorbing fluid, and has an outer surface for dissipating hear from the fluid carried by the inner passage. The engine mounting assembly mounts the engine to the chassis, includes a resilient member to dampen engine vibration, and includes a connector operatively connected to the engine that directly connects to the reinforced portion of the heat exchanger to mount the engine to the chassis. 
   Other embodiments of the invention relate to a snowmobile having a chassis, an engine, a heat exchanger, and an engine mounting assembly. The heat exchanger is mounted to the chassis and includes a reinforced portion positioned adjacent to a chassis wall to increase the rigidity of the chassis wall. The heat exchanger contains an inner passage for carrying heat absorbing fluid and also has an outer surface for dissipating heat from the fluid in the inner passage. The engine mounting assembly mounts the engine to the chassis, and includes a connector that connects together the engine, the reinforced portion of the heat exchanger, and the chassis wall to support the engine in place. 
   Certain embodiments of the invention relate to a snowmobile having a chassis, an engine, and a heat exchanger. The heat exchanger includes a sealed inner passage for carrying heat absorbing fluid and includes an outer surface for dissipating heat from fluid carried by the inner passage. The heat exchanger is formed with an open-air interior cavity to increase the rigidity of the heat exchanger. The heat exchanger is mounted to the chassis to increase the rigidity of the chassis. 
   Certain embodiment of the invention relate to an integrated engine mount and heat exchanger for a snowmobile that includes an outer surface, an inner passage, and a reinforced engine mount portion. The outer surface has cooling fins for dissipating heat from within the heat exchanger. The inner passage is for carrying a heat absorbing fluid. The reinforced engine mount portion has an aperture for receiving and connecting to an engine mount connector. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a snowmobile of certain embodiments of the present invention. 
       FIG. 2  is a perspective view of a snowmobile chassis of certain embodiments of the present invention. 
       FIG. 3  is an exploded view showing an engine and an engine mount assembly of certain embodiments of the present invention. 
       FIG. 4  is an exploded view showing a snowmobile cooling system incorporating a heat exchanger according to certain embodiments of the present invention. 
       FIG. 5  is sectional view of a heat exchanger according to certain embodiments of the invention. 
       FIG. 6  is a sectional view of a snowmobile chassis incorporating a heat exchanger and engine mount assembly according to certain embodiments of the invention. 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   Referring to  FIG. 1 , a snowmobile  10  is depicted having an endless track  12 , a seat  14 , a chassis  16 , a handlebar  18 , a pair of front steerable skis  20 , and a front suspension system  22 . The seat  14  accommodates seating an operator in straddle fashion. The handlebar  18  is provided for use by the operator and is positioned forward of the operator&#39;s seat. The handlebar  18  is conventionally connected to the skis  20  for steering the snowmobile  10 . A front suspension system  22  suspends the skis  20 . The skis  20  are positioned at the laterally outermost end portions of suspension arms  24 , which suspension arms  24  often have, e.g., shock absorbers with coil springs, to absorb vibrations as the snowmobile passes over uneven terrain. The skis  20  and the suspension arms are constructed so that the skis  20  can be pivoted laterally to steer the snowmobile, e.g. by turning the handlebars  18 . 
   Rearwardly of the skis  20  and beneath the seat  14 , the chassis  16  suspends an endless track  12  by a rear suspension system  26 . The endless track  12  is a propulsion-providing track system and is laterally centrally mounted under the chassis  16  in a longitudinally extending drive tunnel  28 . The track  12  is driven by the engine  30  positioned in the bulkhead  32  ( FIG. 2 ). The track  12  is a belt-type tread that rotates around the periphery of the rear suspension system  26  to propel the snowmobile  10  through the snow. The belt-type tread has a plurality of spaced ribs that extend from the exterior surface of the track  12 . The ribs provide traction to the endless track  12 . Any suitable endless track system may be used with the present invention. 
   The rear portion of the snowmobile includes the rear suspension system  26  for supporting the rear portion of the snowmobile  10  and defining the path of the track  12  that propels the sled across the snow. The rear suspension includes a front suspension arm and a rear suspension arm, each such arm extending downwardly and rearwardly from pivotal connections to the chassis. The lower end of each such arm is secured, directly or indirectly, to the suspension rails, beneath which the track slides. Springs and shock absorbers are typically provided to urge the slide rails down and away from the snowmobile tunnel, the springs and shocks acting to control the relative movement of the suspension with respect to the tunnel as the snowmobile moves over terrain of varying contours. The relative lengths and orientation of the suspension arms also control the movement and orientation of the suspension as it is compressed upwardly toward the tunnel. Any suitable rear suspension system may be used with the present invention. 
     FIG. 2  illustrates a chassis  16  in accordance with the present invention. Beneath the operator&#39;s seat area and disposed around the endless drive track, the snowmobile  10  has a longitudinally extending drive tunnel  28 . The drive tunnel includes a longitudinally extending top panel  34 , which extends the length of the drive tunnel. The top panel  34  connects to generally downwardly extending sidewalls  36  that are positioned on opposite sides of the endless track so that the endless track is disposed within the drive tunnel. The panel  34  and extending sidewalls  36  may comprise a single sheet of material formed into the inverted U-shape of the drive tunnel. Preferably, the drive tunnel is constructed of aluminum. 
   The forward portion of the chassis  16  defines the bulkhead  32  for supporting the engine. The rear section of the bulkhead  32  includes a close-off panel  38  that is generally transverse to the vehicle and extends between the sidewalls  36  of the drive tunnel  28 . 
   With reference to  FIG. 3 , the engine  30  is mounted within the bulkhead  32  through a mount assembly  40 . The mount assembly  40  includes engine support brackets  42  or straps that have two apertures  44  on the central portion of each bracket  42  and an end aperture  46  on each end of each bracket  42 . Apertures  44  receive bolts  48  to fasten the support brackets  42  to the engine  30 . The engine  30  and brackets  42  are mounted to the vehicle via the use of vibration absorbing elements  50 . Vibration absorbing elements  50  are formed of a resilient element  52  (e.g., cylindrical, rectangular, etc.) sandwiched between top and bottom mounting studs  54 ,  56 . End apertures  46  receive the top mounting studs  54  and are secured into place about the engine support bracket using nuts  118  and washers  120  so that the vibration absorbing elements  50  are fastened to and support the engine support brackets  42 . The bottom-mounting studs  56  may be attached to the vehicle as described below. It is understood, however, that other engine mounting assembly configurations are within the scope of embodiments of the invention. For instance, resilient element  52  could be eliminated or relocated to the interface between brackets  42  and engine  30 . In addition, brackets  42  could be eliminated or incorporated into the engine itself, such that the vibration absorbing elements are mounted directly into the engine. 
   In certain embodiments, the engine  30  is liquid-cooled by a liquid cooling system  58 , which contains internal passages for carrying liquid coolant that absorbs heat created by the engine during operation. A pump circulates liquid coolant (usually a water-ethylene glycol mixture) from the internal passages of the engine (where heat generated by the engine would be absorbed by the coolant) to several heat exchangers, where heat is dissipated. The engine drives the pump. The coolant flows in a closed path or fluid circuit back to the engine  30 . Referring to  FIG. 4 , coolant is pumped out from the engine into a hose  60 , through overflow reservoir bottle  62 , through hoses  64  and  66 , and then into the inlet  68  of wear strip cooler  70 . Wear strip coolers  70 ,  72  are positioned within tunnel  28  on the underside of top panel  34 . The wear strip cooler  70  is positioned on the right side of the tunnel  28  wherein the wear strip cooler  72  is positioned on the left side of the tunnel  28 . From the wear strip cooler  70 , the coolant flows out of outlet  74  into a crossover tube  76 . From tube  76 , coolant flows through an inlet  78  into a third heat exchanger, wear strip cooler  72 . From the wear strip cooler  72 , the coolant flows out of outlet  80  and into tube  82 . From tube  82 , coolant flows into the inlet  84  of heat exchanger  86 , which is a front heat exchanger positioned on the front portion of the drive tunnel. Coolant then circulates in a serpentine fashion through heat exchanger  86 , as described further below, and flows out the outlet  88  of heat exchanger  86  and into another tube  90 . Tube  90  leads back to the engine  30 . The engine  30  includes a pump to circulate the liquid coolant. However, the pump could instead be separate from the engine as is known. Other coolant circulation designs are within the scope of the invention. For instance, the circulation designs disclosed in U.S. Pat. Nos. 6,681,724 and 6,109,217, both assigned the assignee of the present invention hereby incorporated herein by reference, could be used in certain embodiments of the present invention. 
   Each of the heat exchangers is preferably made of a thermally conductive material such as aluminum that allows heat to be conducted from the coolant to the heat exchangers. The side coolers  70 ,  72  are preferably made of extruded aluminum. 
   A sectional view of heat exchanger  86  is depicted in  FIG. 5 . The heat exchanger  86  also functions as an engine mount and is configured to support the engine. In addition, heat exchanger  86  is designed to be a relatively rigid or stiff structure. By connecting the relatively rigid heat exchanger  86  to the chassis  16 , heat exchanger increases the rigidity of the chassis and reinforces it to prevent bending, buckling, or twisting of the chassis under normal operating stresses and loads. With reference to  FIG. 5 , in the illustrated embodiment, the heat exchanger  86  has an inlet via tube  84  and an outlet via tube  88 . Heat exchanger  86  includes a sealed hollow cooling conduit  92  for receiving and holding fluid (e.g., coolant). Cooling conduit  92  is a sealed reservoir that holds the coolant or other fluid within its interior passage defined by the interior faces of the walls of the conduit  92 . The cooling conduit  92  is “L-shaped” as shown in  FIG. 5 . However, as described below, other shapes are within the scope of the invention. 
   Cooling conduit  92  includes support bars  94  and  96 . Support bars  94  and  96  provide additional reinforcement and support for exchanger  86 . Support bars  94  and  96  split cooling conduit  92  into three sections, sections  92   a ,  92   b , and  92   c . However, support bars  94  and  96  have channels or apertures machined into them to provide fluid communication paths between conduit sections  92   a ,  92   b , and  92   c . In this way, coolant flows in a serpentine manner through sections  92   a ,  92   b , and  92   c  and the apertures in support bars  94  and  96  that fluidly connect these conduit sections. In alternate embodiments, support bars  94  and  96  could be eliminated, providing a single reservoir  92  within heat exchanger  86 . In other embodiments, the flow path through heat exchanger  86  may be modified as is known. One or more fins  98  are provided on an external surface of the heat exchanger  86 . The fins  98  are preferably formed integrally with the heat exchanger  86  and extend outward from the heat exchanger  86  as is known in the art. During operation of the snowmobile, snow and air are circulated by the drive track within the drive tunnel and the snow can accumulate on the fins  98 . A heat transfer occurs between the cold snow on the outer surface and the warm coolant within conduit  92 . Conduction through the heat exchanger  86  cools the coolant that is circulated through heat exchanger  86 . 
   As may be seen in  FIG. 5 , heat exchanger  86  includes a reinforced portion  100  that closes the ends of the cooling conduit upon itself for added strength and rigidity. That is, reinforced portion  100  extends between the legs of the L-shaped cooling conduit  92  to form a generally triangular-shaped cross-section shown in  FIG. 5 . By closing the heat exchanger on itself, reinforced portion  100  creates a heat exchanger  86  having increased rigidity. A hollow cavity  102  is created interior to the reinforced portion  100  but exterior to the cooling conduit. Stiffening ribs  104  are located within the cavity  102  for increasing the stiffness or rigidity of heat exchanger  86 . Such ribs span the heat exchanger  86  from its right to left extents on the vehicle to increase the strength of the heat exchanger  86 . Ribs  104  also provide increased heat exchanging surface area. As will be described below, the single layer of reinforced portion  100  more easily permits the inclusion of a threaded aperture or receptacle  106 . This threaded aperture  106  is used for receiving and retaining mounting stud  56  of the vibration-absorbing element  50  described above. In this respect, the engine mounting assembly connects to and mounts to heat exchanger  86 , and heat exchanger  86  provides rigidity to support the engine in position. Although not shown in the cross-section in  FIG. 5 , heat exchanger  86  includes two threaded apertures  106 , one on the right side of the heat exchanger  86  and one on the left side of the heat exchanger  86 . In this respect, heat exchanger provides mounting receptacles for both the right and left engine straps  42  shown in  FIG. 3 . 
   As shown in  FIG. 5 , heat exchanger  86  also includes an upper and lower panel mounting portions  108  and  110  that, as are described below, are used to mount heat exchanger  86  to the vehicle chassis. In certain embodiments, the heat exchanger  86  is formed as a single piece. Most of heat exchanger  86  may be formed from a single extrusion in the shape of the cross-section shown in  FIG. 5  for increased strength. End plates  112 , as shown on heat exchanger  86  in  FIG. 4 , may be added to the right and left ends of the extrusion to close and seal off conduit  92 . End plates do not seal off and close cavity  102 , however, allowing for airflow through this cavity to provide additional cooling. Of course, in other embodiments, end plates could seal off and close cavity  102  as well as conduit  92  ends. By creating the reinforced portion  100  and the conduit  92  as one part as opposed to two parts reduces material and assembly cost. Of course, in other embodiments, additional parts can be joined together to form the heat exchanger  86 . 
   A section view of the chassis  16  incorporating the heat exchanger  86  and engine mount assembly  40  according to certain embodiments of the invention is shown in  FIG. 6 . Heat exchanger  86  is mounted on the rearward side of close-off panel  38  via the use of rivets  114  that extend through upper and lower panel mounting portions  108  and  110 . Upper rivet  114  extends through the close-off panel  38  and lower rivet  114  extends through the floor portion  116  of the bulkhead  32  of the chassis  16 . Mounted in this position, reinforced portion  100  of heat exchanger  86  partly conforms to and rests against the rearward side of close-off panel  38 . The reinforced portion  100  lends rigidity to this portion of the close-off panel  38 . That is, the rigidity of heat exchanger  86  mounted in this manner restricts close-off panel  38  from bending or twisting due to movement of the engine  30  or from stresses and loads placed on the chassis during normal snowmobile operation. Heat exchanger  86 , mounted in this manner, is designed to add rigidity to the entire chassis  16  beyond merely the close-off panel  38 . The heat exchanger  86 , including its reinforced portion  100 , provide a rigid structure due to several of its design features, including that its closure onto itself that forms open-air cavity  102 , its stiffening ribs  104 , internal support bars  94  and  96 , unitary design (e.g., cross-section formed of a single extrusion or a single piece), metal construction, etc. The relative rigidity of the heat exchanger  86  is then used to reinforce the entire chassis based on the manner and placement of the mounting of heat exchanger  86  to the chassis. For instance, since heat exchanger  86  mounts to multiple panels that form the bulkhead  32  portion of the chassis  16  (e.g., close-off panel  38 , floor portion  116 ), the rigidity of heat exchanger  86  reinforces multiple portions of the chassis  16  to strengthen the entire chassis. The added strength and stiffness helps prevent the chassis  16  from bending, twisting or buckling under normal operating loads. 
   As shown in  FIG. 6 , vibration-absorbing element  50  connects engine support bracket  42  to heat exchanger  86  through a hole in close-off panel  38 . Bottom stud  56  of element  50  extends through the hole in panel  38  and threadably engages threaded aperture  106  in heat exchanger  86 . Upper mounting stud  54  of element  50  extends through the rearward end aperture  46  in engine support bracket  42  and is bolted in place via nut  118  and washer  120 . Resilient member  52  is positioned in between bracket  42  and close-off panel  38 . Of course, connectors other than element  50  may be used to attach bracket  42  to exchanger  86 . Reinforced portion  100  includes a portion  122  spaced slightly away from the rear side of close off panel  38 . Portion  122  permits the insertion and attachment of floor  116  to close-off panel  38  and exchanger  86  via another rivet  114 , as shown in  FIG. 6 . Accordingly, these attachments between the more rigid heat exchanger  86  and the chassis wall formed by close off panel  38  via element  50  and rivets  114  add rigidity to the chassis without the addition of a separate structural member dedicated for this purpose. As engines increase in size and weight, the space savings in the chassis created by integrated engine mount and heat exchanger  86  provided multiple advantages. 
   The forward end of support bracket  42  is mounted to forward portion of chassis  32  via another element  50 . Instead of providing chassis reinforcement via a heat exchanger, chassis  32  is reinforced without a heat exchanger on the forward end of bracket  42 . Although the sectional view shown in  FIG. 6  shows only one support bracket  42 , two such support brackets  42  are used, as shown in  FIG. 3 , one on the right side of heat exchanger  86  and one on the left side of heat exchanger  86 . In this respect, heat exchanger  86  provides mounting receptacles for both the right and left support brackets  42  shown in  FIG. 3 . 
   Accordingly, certain embodiments of the invention provide a heat exchanger extrusion that is used as both a motor mount extrusion and cooling extrusion. The combined extrusion is positioned on the back side of the close off panel  38  of the chassis  16 . One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. For instance, the heat exchanger  86  is described as being connected within the engine coolant circuit that circulates liquid coolant through the engine. However, heat exchanger  86  may be used as a cooler for other purposes. In one embodiment, heat exchanger  86  may be an oil cooler configured in line with the oil coolant circuit for a four-stroke engine to cool the engine oil. In another embodiment, heat exchanger  86  may be an air intercooler configured in a turbocharged engine intake system that cools engine intake air for better compression. 
   Thus, embodiments of the integrated heat exchanger and engine mount are disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.