Abstract:
A vehicle supporting platform can be supported at plural locations (e.g., four locations) from below such that the platform can pivot fore to aft and side to side in response to the impact of wind on a vehicle on the platform. In a desirable form, the platform is suspended by four suspension rods or cables that loosely support the respective corners of a platform supporting structure. The platform supporting structure can be positioned in a bay beneath the floor level. Although a different number of sensors can be used, in one approach there is one aft motion sensor coupled to the front of the floor supporting frame and a wall portion of the bay and two side sensors, one adjacent to the front of the platform and the other adjacent to the rear of the platform. Both of the side sensors can be on the same side of the platform. A double ball joint can be used to couple the sensor to the structure in one embodiment to eliminate off axis loading. A structure such as a locking collar arrangement can be used in an embodiment to facilitate disconnecting the sensor from the platform.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit U.S. Provisional Patent Application No. 60/796,786, filed May 1, 2006. 
     
    
     SUMMARY  
       [0002]     In accordance with certain aspects, a vehicle supporting platform can be supported at plural locations (e.g., four locations) from below such that the platform can pivot fore to aft and side to side in response to the impact of wind on a vehicle on the platform. In a desirable form, the platform is suspended by four suspension rods or cables that loosely support the respective corners of a platform supporting structure. The platform supporting structure can be positioned in a bay beneath the floor level. Although a different number of sensors can be used, in one approach there is one aft motion sensor coupled to the front of the floor supporting frame and a wall portion of the bay and two side sensors, one adjacent to the front of the platform and the other adjacent to the rear of the platform. Both of the side sensors can be on the same side of the platform. A double ball joint can be used to couple the sensor to the structure in one embodiment to eliminate off axis loading. A structure such as a locking collar arrangement can be used in an embodiment to facilitate disconnecting the sensor from the platform.  
       TECHNICAL FIELD  
       [0003]     The technology disclosed herein relates to wind tunnel balances for use in measuring aerodynamic forces and for supporting a vehicle, such as a truck, during wind tunnel testing.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is a perspective view of exemplary support structure for one embodiment of a vehicle wind tunnel balance.  
         [0005]      FIG. 2  is an end view of the embodiment of  FIG. 1 .  
         [0006]      FIG. 3  is a top view of a wind tunnel balance with a vehicle shown schematically on a support surface of the wind tunnel balance.  
         [0007]      FIG. 4  is a closeup view of one of a plurality of supports utilized to suspend the wind tunnel balance from a wall of an underground bay within which the wind tunnel balance support structure is positioned.  
         [0008]      FIG. 5  is a schematic view illustrating an exemplary positioning of a truck on the upper surface of the wind tunnel balance and illustrating an exemplary positioning of load cells used to measure forces arising from wind directed toward the truck when positioned on the balance in a wind tunnel.  
         [0009]      FIG. 6  schematically illustrates forces on a truck subjected to wind when on the wind tunnel balance.  
         [0010]      FIGS. 7 and 8  illustrate exemplary mounting assemblies.  
         [0011]      FIGS. 9 and 10  illustrate an example of a coupling that can be used with one form of a load cell mounting structure to permit decoupling of the load cell from the wind tunnel balance supporting framework. 
     
    
     DETAILED DESCRIPTION  
       [0012]     With reference to  FIGS. 1 through 4 , an exemplary form of wind tunnel balance for vehicles in accordance with this disclosure is shown. In this example, a supporting frame structure, such as a frame  10 , carries a vehicle supporting surface  12  which is desirably has a planar upper surface and can be formed of, for example, sheets of ⅝ inch aluminum decking secured to a frame. An exemplary balance deck  12  is sized to support heavy duty trucks with an exemplary dimension being 12′×30′.  FIG. 3  illustrates a schematic version of a truck  14  having front wheels  16 , 18  and sets of rear wheels  20 , 22 , 24  and  26  coupled to respective tandem axles  28 , 30 . Desirably, deck  12  is substantially flush with or in the plane of a floor portion of the wind tunnel  34  that is spaced from the deck by a perimeter gap  36 . The wind tunnel is provided with a frame receiving under floor level bay within which the frame  10  is positioned. The illustrated bay comprises first and second spaced apart parallel upright side walls  50 , 52 , front and rear walls  54 , 56 , and a floor  60 . The walls  50 , 52  are supported by respective footings  62 , 64 .  
         [0013]     The frame  10  supports the deck  12  so as to float (move fore and aft, side-to-side and twist) relative to the floor and within the gap  36  in response to forces applied by wind impacting a vehicle positioned on the deck. In accordance with this disclosure, a four point pendulum support approach is used. With reference to  FIG. 3 , and as will be more apparent from the discussion below, the frame  10  is suspended at four locations  70 , 72 , 74  and  76 . Desirably, elongated supports coupled to walls of the bay are used to hang the frame at the respective locations  70 , 72 , 74  and  76 . As a specific approach, four elongated rods are utilized to suspend the frame, each rod having an upper end coupled by a bracket mounted to one of the walls and a lower end coupled to the frame.  
         [0014]     The illustrated frame  10  comprises first and second parallel spaced apart longitudinally extending supports, such as I-beams  100 , 102 . In addition, spaced apart lateral or transversely extending deck supports, such as beams  108 , are carried by the respective I-beams  100 , 102  with the deck  12  being positioned on top of the supports  108 . The supports  108  desirably comprise I-beams at two foot intervals along the length of the longitudinally extending beams  100 , 102 . The outermost ends of the supports  108 , as indicated for one such end  110 , are notched at their underside to provide a clearance gap above the upper end of the associated side wall (e.g., wall  50 ). As can be seen in  FIG. 2 , the ends of support  108  overlap the respective upper ends of the walls  50 , 52 . In the event the frame  10  were to fail, or become overloaded, the walls  50 , 52  would prevent the deck  12  from falling into the bay.  
         [0015]     A first suspension structure is provided to support the front end portions of beams  100 , 102  and a similar second rear suspension structure is used to support the rear end portions of the beams  100 , 102 . The suspension structures can be identical and for this reason only the front suspension structure will be described.  
         [0016]     More specifically, with reference to  FIGS. 1, 2  and  4 , the illustrated front suspension structure comprises first and second upright, in this case vertical, supports  130 , 132 . Supports  130 , 132  can, for example, be box beams of tempered steel that are 4″×4″ wide by ⅜″ thick, although these dimensions and material can be varied. A cross member  136 , which can be of the same material as uprights  130 , 132 , extends across the lower portion of the suspension structure with outer end portions  138 , 140  of cross member  136  extending transversely beyond the lower ends of the respective uprights. Respective connectors, such as base plates  142 , 144 , are positioned underneath the respective end portions of cross member  136  and the lower end portions of the respective supports  130 , 132 . Respective upright connectors, such as gusset plates  146 , 148 , extend upwardly from the respective plates  142 , 144 . In this example, the gusset  146  is positioned against the front surface of upright  130  and the rear surface of cross member  136  and the gusset  148  is positioned against the upper surface of upright  132  and the rear surface of cross member  136 . These components can be secured together, such as by welding, to provide a rigid interconnected structure. Upwardly angled front and rear braces or reinforcements  180 , 182  can be secured at the lower ends to the structure including gusset plate  142  and at their upper ends to the undersurface of beam  100 . Gussets can also be used to assist in securing the upper ends of the braces  180 , 182  to the I-beam  100 . One such gusset is shown at the upper end of support  182  in  FIG. 1 . Similar braces can also be positioned for connection from the structure including gusset  144  to I-beam  102 . Supports  180 , 182  can, for example, be angle beams.  
         [0017]     Respective cross supports are also included in the front suspension structure of this example. These cross supports can comprise respective cross members  200 , 202 , such as angle beams. Cross members  200 , 202  are desirably secured together at their intersection, such as by welding to a connection plate or gusset  204 . The lower end portion of cross member  200  is secured, as by welding, to gusset  146  and the upper end portion of cross member  200  is secured, as by welding, to a reinforcing gusset  210  mounted to I-beam  200 . In the same manner, the lower end portion of cross member  202  is secured, as by welding, to gusset  148  and the upper end portion of cross member  202  is secured, as by welding, to a gusset  212  mounted to I-beam  100 . It should be noted, however, that other connection approaches and support structures can be used. The illustrated structure does provide a desirable rigid framework for supporting the deck  12 .  
         [0018]     As previously mentioned, the frame  10  and thus the deck  12  is supported so as to float within the bay during normal operation of the wind tunnel balance. This floating support is accomplished by four elongated supports, such as cables or rods suspending the structure from components forming the bay. In the specifically illustrated approach, both the front and rear suspension structures are supported in the same manner. Therefore, only the front support approach of this example will be described. With reference to  FIGS. 2 and 4 , respective wall mounted brackets  220 , 222  are bolted or otherwise mounted to the side walls  50 , 52  of the bay. These brackets each comprise a respective upright horizontally extending support flange  224 , 226  and a respective wall mounting flange  228 , 230 . Wall mounting flange  228  abuts the surface of wall  50  whereas wall mounting flange  230  abuts the surface of wall  52  in this example. Each of the brackets  220 , 222  also comprises a respective upright reinforcing flange  232 , 234 . A first rod  260 , which may be threaded along its length, has its upper end portion inserted through an opening in flange  224  with one or more nuts being secured to the rod at its upper end to prevent the rod from passing downwardly through the bracket. The lower end of rod  260  extends through an opening in gusset  142  and is secured from below by one or more nuts. A similar rod  262  is secured in the same manner to bracket flange  226  and the gusset  144 . With four such support rods being provided, two at the front and two at the rear for suspending the respective front and rear support structures and thereby the deck, the deck is floatingly supported at the four locations  70 , 72 , 74  and  76  (see  FIG. 3 ) to allow movement of the deck within limits in response to wind impacting a truck positioned on the deck in the wind tunnel.  
         [0019]     Respective locking pins (shown schematically at  297  in  FIG. 5 ) may be inserted through openings in the deck and into brackets (shown schematically at  299  in  FIG. 5 ) coupled to the walls to prevent the deck from shifting at selected times, such as when the wind tunnel balance is not in use.  
         [0020]     Desirably, the gap  36  is uniform and a uniform clearance is provided from the platform to the pit (such as ¼″ clearance). Exemplary support rods  260 , 262  are ⅝″ threaded support rods.  
         [0021]     A plurality of load cells couple the framework to the adjacent walls of the bay. Although any number of load cells can be used, desirably three such load cells are employed. With reference to  FIGS. 3 and 5 , two of the load cells  280 , 282  are positioned between wall  50  and the frame at respective fore and aft locations along the wall. In addition, a load cell  284  is positioned at the front of the structure extending between wall  54  and the frame and positioned along the longitudinal center of the wind tunnel balance. These load cells can be of any suitable type with a specific example being strain gauge containing load cells that provide an electrical signal indicative of the force detected by the load cell. A specific exemplary load cell is a Honeywell Model No. 41 Sensotech Precision Pancake load cell. These load cells can be used to determine drag, side forces and yawing moments in response to wind directed against a vehicle in the wind tunnel. For example, with reference to  FIG. 6 , drag corresponds to forces in the direction of arrow  300  in response to wind impacting the vehicle, side forces correspond to forces in the direction of arrow  302  in response to side directed wind components, and the yawing moment corresponds to twisting forces in the direction indicated by arrow  304 . Forces measured by the load cells are used to compute drag, side forces and yawing moments in response to wind impacting the vehicle in the wind tunnel.  
         [0022]     With reference to  FIGS. 7-10 , exemplary load cell coupling structures are illustrated. In  FIG. 7 , the load cell  284  is shown coupled to a mounting block  310  that is mounted to wall  54 . A rod structure  312  is coupled at one end  314  by a ball joint to the load cell and at the opposite end  316  by another bolt ball joint to a clevis support  318 . Support  318  is mounted by a support structure  320  to the undersurface of two of the cross beams  108 . In addition, with reference to  FIG. 8 , the load cell  280  is mounted by a support  330  to the wall  350 . A coupling rod structure  332  is coupled at a first end portion by a ball joint  334  to the load cell  280  and at a second end portion  336  by a ball joint to a clevis structure  338  mounted to a cross piece  340 . Cross piece  340  is coupled to one of the I-beams  108  (not shown in  FIG. 8 ). The use of double ball joints to connect the respective ends of the support pin structures to their associated load cells and mounting brackets eliminates off-axis loading of the load cells. This structure can be altered if desired, for example, if more load cells are used.  
         [0023]     The pin structures  312  and  332  can be identical and may comprise a one piece pin. However, more desirably, with reference to  FIGS. 9 and 10 , the pin structures (described for structure  312 ) comprises a first pin section  360  with a first end portion coupled to the load cell and a second end portion  362  inserted into a locking collar  364 . In addition, a second pin section  370  has one end portion coupled to the deck mounting framework and the opposite end portion  372  coupled to the locking collar. Although other coupling mechanisms can be used, an exemplary locking collar  364  comprises a machinable-bore, one-piece, clamp-on, coupling from McMaster-Carr. With this particular locking collar, the loosening of set screws  380  allows the end portion  372  to be removed from the locking collar to thereby separate the load cell from the deck. This can be done, for example, to facilitate changing of the load cell or to protect the load cell at times when the load cell is not being used to measure forces.  
         [0024]     Although the wind tunnel balance described herein may be used in any suitable wind tunnel, an exemplary wind tunnel is set forth in U.S. Pat. No. 6,820,477, a copy of which is included herewith and forms a portion of this disclosure.  
         [0025]     In this disclosure, the terms “a”, “an” and “at least one” include one and also more than one of the referenced components. Also, the term “coupled” encompasses direct connections and indirect connection through one or more other components.  
         [0026]     Having illustrated and described the principles of our invention with reference to illustrated embodiments, it should be apparent to those of ordinary skill in the art that these embodiments can be modified in arrangement and detail without departing from the inventive principles disclosed herein. We claim all such modifications.