Patent Publication Number: US-2007108834-A1

Title: Balance weight cartridge with enclosed balance media

Description:
This application is a continuation in part of U.S. non-provisional patent application Ser. No. 11/276,867, filed Mar. 17, 2006, which is a continuation in part of U.S. non-provisional patent application Ser. No. 11/306,397, filed Dec. 27, 2005, which is a continuation of U.S. non-provisional patent application Ser. No. 10/806,671, filed Mar. 23, 2004, now U.S. Pat. No. 6,979,060, issued Dec. 27, 2005, which claims the benefit of U.S. provisional patent application Ser. No. 60/488,634, filed Jul. 18, 2003; all of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD  
      This invention relates to the reduction of vibration in tire/wheel assemblies operating under different speeds and changing tire properties.  
     BACKGROUND  
      A motor vehicle may be characterized as comprising an unsprung mass and a sprung mass. The unsprung mass includes parts of the vehicle not supported by the vehicle suspension system such as the tire/wheel assembly, steering knuckles, brakes and axles. The sprung mass, conversely, includes parts of the vehicle supported by the vehicle suspension system. The unsprung mass can be susceptible to disturbances and vibration from a variety of sources such as worn joints, misalignment of the wheel, brake drag, irregular tire wear, etc. Because vehicular tires support the sprung mass of a vehicle on a road surface and such tires are resilient, any irregularities in the uniformity or dimensions of the tire, any dimensional irregularities in the wheel rim, and/or any dynamic imbalance or misalignment of the tire/wheel assembly may cause disturbances and vibrations to be transmitted to the sprung mass of the vehicle thereby producing an undesirable or rough vehicle ride, as well as reducing handling and stability characteristics of the vehicle. Severe vibration can result in undesirable conditions such as wheel tramp or hop and wheel shimmy (shaking side-to-side).  
      It is now standard practice to reduce some of these adverse vibrational effects by balancing the wheel rim and tire assembly by using a balance machine and clip-on lead weights or lead tape weights. The lead balance weights are placed on the rim flange of the wheel and clamped in place in a proper position, or adhered to the wheel in the case of tape weights, as directed by the balancing machine. By one definition, balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. A balanced tire/wheel assembly is one where the mass of the tire/wheel assembly mounted on the vehicle&#39;s axle is uniformly distributed around the axle. Balancing is an improvement that reduces the vibration of the tire/wheel assembly in comparison to an unbalanced tire/wheel assembly.  
      However, even perfect balancing of the tire/wheel assembly does not necessarily mean that the tire will roll smoothly. Even a perfectly balanced tire can have severe vibrations due to non-uniformities in the tire, which result in unequal forces within the tire footprint.  
      A level of non-uniformity is inherent in tires. In the art of manufacturing pneumatic tires, rubber flow in the mold or minor differences in the dimensions of the belts, beads, liners, treads, plies of rubberized cords or the like, sometimes cause non-uniformities in the final tire. These non-uniformities can be determined using force variation machines which measure the forces acting on a tire under load. Forces on a tire that is rolling under load on a road may be broken down into three orthogonal components, which will be referred to herein as: radial, lateral, and tangential. Radial forces act in the tire&#39;s radial direction, i.e., perpendicular to the tire&#39;s axis of rotation. Radial forces are strongest in the vertical direction (e.g., wheel “hop”) as the tire interacts with the road surface, but may also have a horizontal (fore-aft, or “surge”) component due to, for example, the radial centrifugal force of a net mass imbalance in the rotating tire. Lateral forces act in a direction parallel to the tire&#39;s axis of rotation, and generally occur where the tire&#39;s surface touches the road surface. Lateral force causes either tire wobble or a constant steering force. Tangential force, or fore-aft force is experienced at the surface of contact between tire and road surface in a direction both tangential to the tire&#39;s outer circumference (e.g., tread surface) and perpendicular to the tire&#39;s axis of rotation (thus also perpendicular to the radial and lateral forces). Tangential force variations are experienced as a “push-pull” effect on a tire. When non-uniformities are of sufficient magnitude, they cause force variations on a surface, such as a road, against which the tires roll and thereby produce vibrational disturbances in the vehicle upon which the tires are mounted. Regardless of the cause of the force variations, when such variations exceed an acceptable minimum level, the ride of a vehicle utilizing such tires may be adversely affected.  
      Contrary to radial force variations, which are generally not speed dependent, tangential force variations vary greatly with speed. Tangential force variations are generally insignificant below 40 mph; however, tangential force variations surpass radial force variations as the dominant cause of unacceptable vibration of a balanced tire rotating at over 60 mph and can quickly grow to be a magnitude of twice the radial force variation at speeds approaching 80 mph. Currently, there are no viable methods for reducing tangential force variations. Studies have shown that grinding does not reduce tangential force variation (Dorfi, “Tire Non-Uniformities and Steering Wheel Vibrations,”  Tire Science  &amp;  Technology , TSTCA, Vol. 33, no. 2, April-June 2005 p 90-91).  
      Tire uniformity machines are relatively expensive, and their use is generally limited to tire companies and automotive vehicle companies. Tire shops try to minimize the effect of tire non-uniformity by matching up the harmonic high point of the tire (typically marked with a yellow dot representing the lightest part of the tire) with the harmonic low point of the rim (typically the valve stem representing the heaviest part of the wheel). This requires that the tire manufacturer and the wheel manufacturer measure and mark these locations on each of their products in a standard fashion and that the mark does not get removed in some manner over the life of the tire and wheel. Even if this is done, the tire shop has no knowledge of the magnitude of the non-uniformity of the tire. Therefore, if the tire/wheel assembly is balanced and matched but the vibration problem persists, the tire shop may recommend a different tire.  
      The tire non-uniformity vibration problem has proliferated with the introduction of ever larger passenger and light truck tires that are installed on sports utility vehicles, luxury vehicles, and light trucks. In order to be capable of handling these non-uniformity problems, many tire shops are turning to balancing machines such as the Hunter® GPS9700 balancer, which provides the capability to measure radial force variation, a significant factor in vibration caused by tire non-uniformity. The GPS9700 Road Force Measurement® System uses a roller to apply up to 1,400 lbs. of pressure against the tire/wheel assembly. The load simulates the weight of the vehicle. As the tire is rotated, the equipment measures the variations in the tire&#39;s radial force. Using this information, the operator can use the measured data which includes the high harmonic area on the tire to match together with the low harmonic spot on a rim to cancel vibration caused by radial force variation in the same manner discussed above. After the tire is matched to the wheel, the tire/wheel assembly can be balanced and then rechecked to determine the resulting radial force variation. Using balancing machines such as the GPS9700 provides a magnitude of radial force variation for the tire. Published limits indicate that the radial force variation that most vehicles will tolerate is 18 lbs or less for tires on passenger cars, 24 lbs or less on light trucks, and 30 lbs or less for LT tires on light trucks. These can be stringent limits for tire manufactures with regard to limiting their scrap tire production. Further, some tire manufacturers dispute results from some machines, such as the Hunter® GPS9700 balancer.  
      While gains have been made in the ability of an average tire shop to diagnose, measure, and correct vibration of a tire/wheel assembly due to imbalance, run out, and non-uniformity force variations, there remains a need in the art to provide stability to the unsprung mass of the vehicle to combat tires that may have excessive force variations due to non-uniformity. Accordingly, a weight for a tire/wheel assembly is needed for reducing vibration in tire/wheel assemblies operating under different speeds and changing tire properties.  
     SUMMARY OF THE DISCLOSURE  
      At least one disadvantage of the prior art is overcome by providing a weight comprising a receptacle having an opening, a flowable media at least partially filling the receptacle, a lid capable of closing the receptacle, and an adhesive on an exterior surface of the receptacle or the lid.  
      A tire/wheel assembly disclosed may comprise a wheel rim, a tire mounted on the wheel rim, and a weight mounted onto a non-pressurized side of the wheel rim, the weight comprising a tray comprising a receptacle, a flowable media at least partially filling the receptacle, a lid closing the receptacle and being affixed to the tray, and an adhesive on an exterior surface of the weight attaching the weight to the wheel rim.  
      A method of attaching a single weight to a tire/wheel assembly may comprise the steps of providing a tire/wheel assembly; providing a single weight comprising a tray comprising a receptacle, a flowable media at least partially filling the receptacle, a lid closing the receptacle and being affixed to the tray, and an adhesive on an exterior surface of the weight; and attaching the weight by the adhesive to a non-pressurized side of a tubewell of the tire/wheel assembly or a non-pressurized side of a rim flange of the tire/wheel assembly, and attaching the weight to the wheel rim about an angle of 180 degrees or less.  
      A method of attaching a plurality of weights to a tire/wheel assembly may comprise the steps of providing a tire/wheel assembly, providing a plurality of weights, each weight comprising a tray comprising a receptacle, a flowable media at least partially filling the receptacle, a lid closing the receptacle and being affixed to the tray, and an adhesive on an exterior surface of the weight, and attaching the plurality of weights to a non-pressurized side of a tubewell of the tire/wheel assembly or a non-pressurized side of a rim flange of the tire/wheel assembly such that the plurality of weights, in combination, do not extend 360 degrees about the rotational axis of the tire/wheel assembly when the weights are attached to the wheel.  
      A tire/wheel assembly disclosed may comprise a wheel rim, a tire mounted on the wheel rim, and a weight mounted onto a non-pressurized side of the wheel rim, the weight comprising a receptacle between two film layers sealed on three or more edges, a flowable media at least partially filling the receptacle, and an adhesive on an exterior surface of the receptacle.  
      In any of the foregoing embodiments, the weight may be flexible between a flat and an approximately arcuate shape. The weight may comprise a tray that was manufactured by thermoforming. The flowable media in the weight may occupy between 5 and 95 percent of the receptacle volume. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of one embodiment of a balance weight of the present disclosure;  
       FIG. 2  is an exploded perspective view of a mounting side of the weight of  FIG. 1 ;  
       FIG. 3  is a cross-sectional view through the weight of  FIG. 1 ;  
       FIG. 4  is an top view of the weight of  FIG. 1 ;  
       FIG. 5  is an elevational side view of the weight of  FIG. 1 ;  
       FIG. 6  is an exploded perspective view of a further embodiment of the balance weight having a circular shape;  
       FIG. 7  is an exploded perspective view of a further embodiment of the balance weight having two interior cavities;  
       FIG. 8  is a perspective view of an embodiment of the balance weight attached to the brake side of the tube well of a tire/wheel assembly;  
       FIG. 9  is a top view showing relative sizes of three embodiments of the weight of the present disclosure;  
       FIG. 10  is a partial side view of a wheel with a further embodiment of the present disclosure mounted to a wheel rim flange;  
       FIG. 11  is a cross-sectional view of the wheel rim flange and weight through the section marked  11 - 11  in  FIG. 10 ;  
       FIG. 12  is a cross-sectional view through a further alternate embodiment of the weight of the present disclosure; and  
       FIG. 13  is a cross-sectional view through an alternate embodiment of the weight of  FIG. 12 . 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Related balance weight embodiments have been disclosed in previous co-owned patent applications, including but not limited to the disclosure of U.S. Pat. No. 6,979,060, issued Dec. 27, 2005, and hereby incorporated by reference. These applications disclosed a tube type of weight cartridge having an interior chamber at least partially filled with flowable material. The present disclosure provides an alternate way to form an inner chamber containing flowable material.  
      Referring now to  FIGS. 1 through 5 , a balance weight  10  is provided comprising an interior chamber  30 . In one embodiment, the weight  10  comprises a receptacle  36  having an opening, forming at least a portion of the interior chamber  30 .  
      In the embodiment of  FIGS. 1 and 2 , the interior chamber  30  is formed between a tray  32  comprising the receptacle  36 , and a lid  34 . The lid  34  is capable of closing the receptacle  36  for retaining a flowable media  40  in the interior chamber  30 . In this embodiment, the receptacle  36  is formed within the tray  32 , and the lid  34  is affixed to the tray  32  to close the receptacle  36 .  
      In an alternate embodiment shown in  FIGS. 12 and 13 , the interior chamber  30  is sealed between a first layer  41  of film material and an adjacent second layer  42  of film material. In this embodiment, the receptacle  36  is created by sealing the perimeter of the adjacent first and second layers  41 ,  42  of film material.  
      In the embodiment of  FIG. 2 , the weight  10  comprises a flange  44  about the receptacle  36 . In one embodiment, the lid  34  is affixed to the flange  44 .  
      One or more adhesive strips  70  may be provided on an exterior surface of the weight for attaching the weight to a wheel. In the embodiment of  FIGS. 1 and 2 , the adhesive strip  70  is provided on an exterior surface of the lid  34  for attaching the weight to a wheel. Alternately, one or more adhesive strips  70  may be provided on an outer surface of the tray  32 . The adhesive may be an acrylic adhesive capable of holding the weight to the wheel in a selected range of tire/wheel assembly operating temperatures. It is contemplated that adhesives other than acrylic may be provided.  
      In this embodiment, the weight  10  may be flexible between a flat and an approximately arcuate shape. Ribs  46  may be provided to facilitate or provide relief for flexing the tray between the flat and approximately arcuate shapes. In one embodiment, the ribs  46  are provided in the receptacle  36 .  
      In the embodiment of  FIG. 1 , the weight is manufactured in a flat shape. Before an operator installs the weight onto a wheel, the operator may flex the weight into a shape that approximately matches the shape of the mounting surface. In one operational embodiment, the weight  10  is mounted to the non-pressurized side of a tubewell of the tire/wheel assembly or a non-pressurized side of a rim flange of the tire/wheel assembly, and the weight is flexed into an approximately arcuate shape that approximately matches the radius of the mounting surface of the wheel.  
      The lid  34  may be a flat sheet, as indicated by  FIG. 2 . In one embodiment, the lid  34  is the same shape as the tray  32 , thereby providing a larger interior chamber  30 . It is contemplated that the lid may comprise any suitable shape for closing the receptacle  36  and forming the interior chamber  30 . In one embodiment, the ribs  46  are formed in the lid.  
      It is contemplated that the interior chamber  30  may be formed by joining two trays  32  together such that the openings of each receptacle  36  face together and the interior chamber  30  comprises a volume approximately the sum of the volume of each separate tray receptacle. In this embodiment, one of the joined trays functions as a lid for the other tray  32 .  
      In the embodiment of  FIG. 5 , the ribs  46  are formed into the tray  32  such that the ribs extend into the interior chamber  30 . In one embodiment, the ribs  46  extend into the tray  32  approximately the depth of the tray to limit the flow of media in the chamber  30 . In one embodiment, the ribs  46  extend in an outward direction to not limit the flow of media through the interior chamber  30 .  
      The tray  32  may be manufactured by thermoforming the tray from a sheet of thermoplastic material, and then die cutting a perimeter around the receptacle  36  to create the flange  44 . After filling the tray receptacle with flowable media  40 , the lid  34  may be affixed to the tray  32  by sonic welding, vibration welding, heat staking, snap fitting features, adhesives, fasteners, or other methods for connecting the lid  34  to the tray  32 .  
      The lid  34  may be connected to one side of the flange  44  by forming and die cutting the lid and the tray as one piece. In this embodiment, after the tray is filled with flowable material, the lid may be folded over to cover the tray receptacle and then affixed to close the tray.  
      The tray and lid may be made from a material suitable for thermoforming, such as but not limited to polyethylene, polypropylene, polyester, PVC, ABS, or other plastic material. In one operating environment, the weight  10  may be exposed to a wide range of temperatures and various chemicals and grime. It is contemplated that the tray and lid may be manufactured with any flexible thermoplastic material having suitable toughness and temperature and chemical resistance. In one embodiment, the tray  32  and lid  34  are made by forming a thin film having a thickness less than 0.010 inch (0.25 millimeter) comprising polyester, polyethylene, or other suitable polymer. In an alternate embodiment, the tray  32  and lid  34  are made from a metallic material.  
      In one embodiment, the tray  32  and lid  34  are manufactured by injection molding. Alternately, the tray  32  and lid  34  may be manufactured by pressure forming, stamping or cold forming, extrusion, or any other suitable manufacturing process for creating the tray and lid.  
      The weight  10  may comprise a tray having a relatively wide receptacle to allow movement of the media adjacent the wheel in both a circumferential direction as well as a lateral direction to balance the wheel in two planes.  
      In one embodiment, the weight  10  is a low-profile configuration, as indicated by  FIG. 5 , which enables the weight  10  to be positioned on the inboard side of the wheel without contacting the brake components.  
      The weight  10  may comprise a logo  48 . The logo shown in  FIGS. 4 and 9  is the XACT BALANCE® trademark. However, it is contemplated that other logos may be provided, including trademarks of retailers, tire manufacturers, suppliers, distributors, or others. The weight  10  may be offered as a marketing premium with custom colors and logos provided. In this embodiment, the logo  48  is provided on a surface of the weight opposite of the adhesive, such that the logo is visible when the weight is mounted to the wheel. The logo  48  may be formed into the receptacle  36  or lid  34 . Alternately, the logo  48  may be applied by hot stamp, heat transfer, label, or any other graphical printing, application, or embossment.  
      In the embodiment of  FIG. 6 , the weight  10  comprises an arcuate shape, such as a circle or oval shape. In this embodiment, an arcuate shaped tray  32 ′ is at least partially filled with flowable media  40 , and closed by a lid  34 ′.  
      In the embodiment of  FIG. 7 , the weight  10  comprises more than one chamber  30 . In this embodiment, the tray  32 ″ has two or more receptacle compartments, designated as  36   a  and  36   b  in  FIG. 4 . The multiple chambers may provide additional structural rigidity by providing an interior wall to further attach the lid. The incorporation of multiple chambers may also limit the movement of the media between receptacle compartments  36   a ,  36   b , which in some instances may help the media to balance the wheel by providing movement of the media in more than one chamber.  
      In the thin film embodiment of  FIG. 12 , the first layer  41  of film material is positioned adjacent the second layer  42  of film material and the sides and bottom edges of the layers are sealed together to form the receptacle  36 , as a pouch, having an opening at the top. Then, the pouch, or receptacle  36 , is filled with an amount of the flowable media  40  to fill between 5 to 95 percent of the volume of the receptacle  36 . In one embodiment, the amount of flowable media  40  exceeds 95 percent of the volume of the receptacle  36 . After the flowable media  40  is placed into the receptacle  36 , the top edges of the layers  41 ,  42  are sealed together to close the interior chamber  30 .  
      Alternately, as shown in  FIG. 13 , the first layer  41  and the second layer  42  may be one piece of film material folded over onto itself, such that the receptacle  36  is created by sealing together the top edges, bottom edges, and the edges on the side opposite of the fold. In this embodiment, the film material is folded over and the bottom and side edges of the layers  41 ,  42  are sealed together to form the receptacle  36 , as a pouch, having an opening at the top. Then the receptacle  36  is filled with the selected amount of the flowable media  40 . After the flowable media  40  is placed into the receptacle  36 , the top edges of the layers  41 ,  42  are sealed together to close the interior chamber  30 .  
      The weight  10  of  FIG. 12  and  13  may further comprise one or more of the adhesive strips  70  provided on an exterior surface of the first layer  41  or the second layer  42 . The logo  48  may be provided on the side opposite of the adhesive  70 . In this embodiment, the logo  48  may be applied by hot stamp, heat transfer, label, or any other graphical printing, application, or embossment.  
      In the embodiments of  FIG. 12  and  13 , the receptacle  36  may be made and filled with a vertical form fill and seal machine known in the packaging industry. In one embodiment, the weight  10  comprises a flexible and resilient thin film having a thickness less than 0.010 inch (0.25 millimeter) comprising polyester, polyethylene, or other suitable polymer.  
      The flowable media  40  may be metallic balls, such as but not limited to stainless-steel. However, any suitable flowable material is contemplated, including beads, shot, particles, powders, etc. made of ceramic material, glass material, polymeric material, metallic material, or other ferrous and non-ferrous metals, ceramics, plastics, glass beads, alumina, etc. It is also contemplated that the flowable material may be a liquid, in whole or in part. Such suitable materials may include any material that is stable and remains free flowing over various operating conditions of the tire/wheel assembly. The size of the individual material of the flowable media  40  is small enough that it can flow in an interior chamber  30  having a relatively small height. It is contemplated that the flowable material may include a lubricating agent such as talc or graphite that may help the material enhance and/or retain its flowable characteristics.  
      Referring now to  FIG. 8 , an embodiment of the balance weight  10  is shown attached to a wheel  50  of a tire/wheel assembly  60  by the adhesive  70 . In some embodiments, the weight may be mounted to aesthetic aluminum alloy wheels where a consumer may not want the weight to be visible. Accordingly, the weight  10  may be mounted to the non-pressurized side of the tubewell  54  or a non-pressurized side of the rim flange of the tire/wheel assembly using the adhesive  70 . Alternately, the weight  10  may be mounted on the inboard side of the spider  52  along the brake side of the tubewell  54  of the wheel  50 . In one embodiment, the weight  10  is longitudinally arcuate when attached to the wheel rim about an angle of 180 degrees or less.  
      In one embodiment, the amount of flowable media  40  within the balance weight  10  is sufficient to enable at least one balance weight  10  to balance the tire/wheel assembly. In use, one or more balance weights  10  may be applied in the same manner as a standard lead balance weight, as shown in  FIG. 8 . In one balancing method, the tire/wheel assembly is mounted on the spin balancer and the out of balance condition is detected. The spin balancer recommends an amount of weight to be positioned at a particular circumferential position and at a particular predetermined distance from the axis in one or more predetermined planes. The mass of one or more balance weight  10  mounted (including the weight  10  and flowable media  40 ) may be equivalent to the amount of weight called for by the balance machine.  
      Various specified weights may be provided by increasing the size of the interior chamber  30  by increasing the size of the tray, as indicated by  FIG. 9 . A variety of predetermined sizes of tray  32  may be provided for achieving different sizes of interior chamber  30 . The amount of flowable media  40  provided in the interior chamber  30  may be proportional to the specified weight with larger imbalances requiring a larger tray  32  and more flowable media  40 , and vise versa.  
      It is contemplated that the amount of flowable media  40  used in the weight  10  may vary between 5 to 95 percent of the receptacle volume. In one embodiment, the amount of flowable media  40  used in the weight  10  may vary between 5 to 95 percent of the volume of the interior chamber  30 . In one embodiment, the amount of flowable media  40  is approximately two-thirds of the volume of the interior chamber  30 . We have found that filling approximately two-thirds of the volume of the interior chamber  30  with flowable media  40  provides optimized dynamic balancing for some tested wheel assembly embodiments. However, any amount sufficient to allow the flowable material to sufficiently move and balance the tire/wheel assembly is contemplated. In some applications where the lead balance weight is merely replaced, more than 95 percent of the receptacle volume may be filled with media  40  such that the balance weight  10  acts as a fixed weight.  
      The weight of the present disclosure may be formed in a shape that conforms to a predetermined surface. In the embodiment of  FIGS. 10 and 11 , the weight  10 ′″ comprises a tray  32 ′″ that is formed in an arcuate shape approximately matching the radius of a wheel flange  56 . In a thermoformed embodiment, the tray may be molded to correspond to any suitable surface on the wheel  50 .  
      It is contemplated that for some tire/wheel assemblies, a single balance weight  10  will be sufficient to balance the tire/wheel assembly. Alternately, for some tire/wheel assemblies, a plurality of balance weights  10  may be used to balance a wheel, as with the prior art lead balance weights. The balance weight  10  is applied in the same manner as are the tape weights as instructed by the particular balance weight machine (not shown), using either single plane or dual plane balancing.  
      The flowable media  40  in the balance weight  10  has the ability to help dampen minor vibration of the tire/wheel assembly due to various causes such as tire uniformity problems. This helps promote a smoother ride for the occupants of the vehicle.  
      While this invention has been described with reference to specific embodiments, it shall be understood that such description is by way of illustration and not by way of limitation. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.