This invention relates to the reduction of vibration in tire/wheel assemblies operating under different speeds and changing tire properties.
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'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's radial direction, i.e., perpendicular to the tire'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's axis of rotation, and generally occur where the tire'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's outer circumference (e.g., tread surface) and perpendicular to the tire'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 & 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'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.
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.
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
In the embodiment of
In an alternate embodiment shown in
In the embodiment of
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
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
The lid 34 may be a flat sheet, as indicated by
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
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
The weight 10 may comprise a logo 48. The logo shown in
In the embodiment of
In the embodiment of
In the thin film embodiment of
Alternately, as shown in
The weight 10 of
In the embodiments of
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
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
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
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
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.
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.
Number | Date | Country | |
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60488634 | Jul 2003 | US |
Number | Date | Country | |
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Parent | 10806671 | Mar 2004 | US |
Child | 11306397 | Dec 2005 | US |
Number | Date | Country | |
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Parent | 11276867 | Mar 2006 | US |
Child | 11559604 | Nov 2006 | US |
Parent | 11306397 | Dec 2005 | US |
Child | 11276867 | Mar 2006 | US |