Abstract:
A improved vehicle wheel balancer for a wheel assembly including an adjustable wheel data acquisition arm configured to transition from at least a first operating position adapted for use with vehicle wheels having a first range of inner diameters, to at least a second operating position adapted for use with vehicle wheels having a second range of inner diameters which differ, at least in-part, from the first range of inner diameters.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a vehicle wheel balancer system or wheel vibration control system configured with an wheel data acquisition arm, and in particular to a wheel data acquisition arm configured with an extended range of motion to accommodate wheel rims of differing inner diameters. 
     Vehicle wheel assemblies, such as shown at  10  in FIG. 1, consist of a pneumatic tire  12  mounted to a wheel rim  14 . The size and configuration of the wheel rim  14  may vary greatly between different vehicle wheel assemblies. These variations may include the number of spokes  16 , the setback of the spokes from the inner edge  18  or outer edge  20  of the rim  14 , the width of the rim  14 , the diameter of the rim  14 , and the shape or contour of the rim  14 . Currently, the U.S. Department of Transportation has approved, for use on passenger cars and light trucks, a maximum wheel rim diameter of 24 inches, however, wheel rim diameters of 26″ or greater are likely to be approved for use in the United States in the near future. 
     Conventional vehicle wheel balancing systems or wheel vibration control systems, such as shown at  30  in FIG. 2, include a central processing unit  32 , such as a general purpose computer, digital signal processor, or other suitable logic circuit, configured with a software application to identify and correct forces and imbalances in vehicle wheel assemblies  10 . The central processing unit  32  receives input from a number of sources, including knobs  34  and keypads  36  for operator input, a memory  38 , and one or more imbalance force sensors  40  disposed in operative relationship to a motor driven spindle or shaft  42  upon which a wheel assembly  10  undergoing a balance procedure is mounted. 
     Imbalance and force measurements, together with other informational output from the central processing unit  32  are displayed to an operator on a video display  44  unit such as a CRT, LCD screen, or LED panel. In addition, the central processing unit  32  is configured to control a motor  46  or other drive unit to regulate the rotational movement and position of the shaft or spindle  42  upon which the wheel assembly  10  is mounted. In some wheel vibration control systems, such as the GSP 9700 Series system, manufactured by Hunter Engineering Co. of Bridgeton, Mo., and shown in FIG. 3, the central processing unit  32  is configured to control a load roller  50  to apply a load to a wheel assembly during rotational movement thereof. The central processor  32  receives feedback from one or more sensors associated with the load roller  50 , indicative of radial or lateral forces exerted by the rotating wheel assembly  10 . 
     One function of a vehicle wheel balancer or vibration control system is to identify, to an operator, the location on a wheel rim at which an imbalance correction weight should be applied to correct a detected imbalance in the wheel assembly. Conventionally, as shown in FIG. 4, a at least one multi-function wheel data acquisition arm  60  is utilized to facilitate the weight placement process. The wheel data acquisition arm  60  is disposed parallel to, and adjacent the shaft or spindle  42  upon which the wheel assembly  10  is mounted. A typical wheel data acquisition arm  60  consists of an extending and rotating shaft  62 , and a perpendicular rim contact arm  64  affixed to an end of the shaft  62 . Alternate designs, such as shown in U.S. Pat. No. 5,447,064 to Drechsler et al., utilize a single telescoping arm secured at a pivot point. A roller or ball  66  is disposed at the end of the rim contact arm  64 , and is configured to provide a known contact point between the wheel data acquisition arm  60  and the wheel rim  14 . Optionally included at the end of the rim contact arm  64  is an imbalance weight holder or clip, configured to hold an imbalance correction weight to aid in placement on a wheel rim  14 . 
     As seen in FIG. 3, some vehicle wheel balancer or vibration control systems  30  include a second, outer wheel data acquisition arm  61  configured with a roller or ball  63 . While the typical wheel data acquisition arm  60  contacts the inner wheel rim  20 , or wheel rim surfaces disposed adjacent the balancer or vibration control system  30  when the wheel rim is mounted to the shaft or spindle  42 , the second or outer wheel data acquisition arm  61  is disposed to contact the outer wheel rim lip  18 . Conventionally, the second or outer wheel data acquisition arm  61  is a fixed length structure capable of rotating through a large arc. 
     During use, with a wheel installed on the balancer shaft or spindle, the shaft  62  of the wheel data acquisition arm  60  is extended such that the perpendicular rim contact arm  64  is positioned within the center portion of the wheel rim  14 . Rotation of the wheel data acquisition arm  60  about the axis of the shaft  62  swings the rim contact arm  64  into contact with an inner surface of the wheel rim  14 , at a known angular position for wheel rims of known diameters. Axial movement of the wheel data acquisition arm  60  is tracked by a displacement sensor  68 , while rotational movement about the axis is tracked by a rotational sensor  70 , with may be either a relative rotational position sensor, or an absolute rotational position sensor. Analog signals from the sensors  68  and  70  are typically converted into digital form via a converter  72 , and routed to the central processing unit  32 . 
     When combined with computer controlled rotation of the wheel assembly  10  about the balancer shaft or spindle  42 , the movement of the wheel data acquisition arm  60  either delivers an imbalance correction weight carried by a weight holder or clip to a calculated angular position on a wheel rim  14 , or provides an operator with a clear visual indication of the weight placement location by contacting the roller or ball  66  at the intended weight placement location. 
     In addition, by tracking the axial movement of the shaft of the wheel data acquisition arm, and the rotational movement of the rim contact arm about the shaft axis, using sensors  68  and  70 , the central processing unit of a conventional wheel balancer system can determine the dimensions, contours, and runout parameters of a wheel rim mounted to the balancer shaft or spindle, as described in U.S. Pat. No. 5,915,274 to Douglas. Determining the dimensions, contours, and runout parameters of the wheel rim permits the central processing unit to identify optimal imbalance correction weight planes, and to present the operator with the best imbalance correction weight arrangement. 
     Using the determined dimensions, contours, and runout parameters of the wheel rim, the central processing unit  32  of the balancer  30  effectively has an infinite number of imbalance correction planes in which to place imbalance correction weights. The best plane locations, amount of weight, and even the number of weights, are calculated to result in a minimized residual static and dynamic imbalance while still using incrementally sized weights. The display  44  associated with the balancer system  30  is used to show the actual scanned contour of the wheel rim  14 , as well as the relative locations of the weights on the displayed wheel rim  14 , enhancing operator understanding and providing confidence that the measuring apparatus is working correctly. However, actual placement of the imbalance correction weights in the identified optimal balance correction planes, and at the ideal rotational positions, must still be done manually by an operator, guided by instructions displayed on the wheel balancer, and aided by the wheel data acquisition arm. 
     The use of a conventional wheel data acquisition arm  60  is, however, limited to wheel rims  14  having an inner diameter in a range between 10.0-22.0 inches, due to mechanical limitations. As seen in FIG. 5, the rim contact arm  64  can rotate about the wheel data acquisition arm shaft  62  between a maximum outward position P max , and a minimum inward position P min . Rotation of the rim contact arm  64  past the maximum outward position P max  reduces the distance between the rim contact arm  64  contact point on the wheel rim  14  and the axis of rotation for the wheel rim about the balancer shaft  42 . Correspondingly, the minimum inward rotational position P min  is defined as the point at which the rim contact arm  64  swing is blocked from further rotation by the balancer shaft or spindle  42  upon which the wheel rim  14  is mounted. 
     Alternative designs for the wheel data acquisition arm  60 , such as shown in U.S. Pat. No. 5,447,064 to Drechsler et al. which telescope from a single pivot point, are capable of contact surfaces of wheel rims  14  having greater ranges of diameters, However, due to the mechanical geometry of these designs, they are incapable of determining, with necessary precision, a pivot angle for the telescoping arm sufficient to permit identification of a wheel rim runout. 
     Accordingly, it will be appreciated that there is a need for a wheel balancer system to include a wheel data acquisition arm which is capable of contacting the inner surfaces of both large and small diameter wheel rims mounted to a balancer shaft or spindle. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, a vehicle wheel balancer system of the present invention incorporates an wheel data acquisition arm configured to transition between at least a first operating position adapted for use with vehicle wheels having a first range of diameters, and at least a second operating position adapted for use with vehicle wheels having a second range of diameters which differ, at least in-part, from the first range of diameters. 
     In an alternate embodiment, the central processing unit of the vehicle wheel balance system is configured to identify the operating position of the wheel data acquisition arm. 
     In an alternate embodiment, the wheel data acquisition arm is further configured with an eccentric roller to generate a cyclic signal when the eccentric roller is in contact with the inner surface of a rotating wheel rim during a runout measurement procedure. The central processing unit of the vehicle wheel balancer system is correspondingly configured to utilize the cyclic signal to estimate a diameter of the wheel rim and to identify an operating position of the wheel data acquisition arm. 
    
    
     The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the accompanying drawings which form part of the specification: 
     FIG. 1 is a perspective view of a conventional wheel assembly; 
     FIG. 2 is a block diagram view of the basic components of a conventional vehicle wheel balancer system; 
     FIG. 3 is a perspective view of a prior art vehicle wheel balancer configured with a load roller and hood; 
     FIG. 4 is a side sectional view of a wheel rim mounted to a balancer spindle, illustrating the range of axial motion of a conventional wheel data acquisition arm; 
     FIG. 5 is an end view of the rotational range of motion for a conventional wheel data acquisition arm; 
     FIG. 6 is an perspective view of an adjustable wheel data acquisition arm of the present invention in the retracted position; 
     FIG. 7 is a sectional view of the adjustable wheel data acquisition arm of FIG. 6, in a retracted position, with the roller and weight clip shown in outline; 
     FIG. 8 is a perspective exploded view of the adjustable wheel data acquisition arm of FIG. 6, in an extended position; 
     FIG. 9 is a sectional view of the adjustable wheel data acquisition arm of FIG. 8, with the roller and optional weight clip removed for clarity; 
     FIG. 10 is an end view of the extended range of motion for an adjustable wheel data acquisition arm of FIG. 6; 
     FIG. 11 is a block diagrammatic view of the various movement sensors associated with the adjustable wheel data acquisition arm of FIG. 6; 
     FIG. 12 is a partial side view of an alternate embodiment roller head; and 
     FIG. 13 is a graphical representation of the cyclical variation in rotational position for an adjustable wheel data acquisition arm configured with the roller head of FIG. 12, during a wheel rim measurement procedure. 
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. 
     Turning to FIGS. 6 and 7, a wheel data acquisition arm of the present invention is shown generally at  100 . The wheel data acquisition arm  100  consists of a shaft  102  adapted for operative coupling to a vehicle wheel balancer system in place of a conventional wheel data acquisition arm, such as shown at  60  in FIGS. 2-5. An adjustable length rim contact arm  104  is secured by a screw  106  to and end of the shaft  102 . The rim contact arm  104  is disposed perpendicular to the longitudinal axis of the shaft  102 , such that rotation of the shaft  102  results in rotation of the rim contact arm  104  through a corresponding arcuate distance. 
     Preferably, the rim contact arm  104  consists of a base  108 , secured at a posterior end  108 A to the shaft  102 , and an extension arm  109  supporting a roller head  110  on a anterior end  109 A. The base  108 , as shown in FIG. 6, supports the extension arm  109  at an angle, displacing the extension arm  109  from the axis of the shaft  102 . The displacement is preferably selected to permit the rim contact arm  104  to have a range of motion which includes access to a region disposed behind the balancer shaft  42 , as best seen in FIG.  5 . Those of ordinary skill in the art will recognize that the angle at which the extension arm  109  is supported by the base  108  is dependent upon the specific geometry of the wheel balancer  60  and the relative placement of the wheel data acquisition arm  100 , as compared to the balancer shaft  42 . In some applications, a greater angle will be required, and in some applications, the base  108  and angle may be eliminated, and the extension arm  109  extended between the shaft  102  and the roller head  110 . 
     The elongated arm  109  is hollow, defining an interior space  118 . The roller head  110  is coupled to the anterior end  109 A of the extension arm  109  by a sliding member  124  disposed within a passage  126  in the extension arm  109 . The sliding member  124  is adapted for sliding movement with the passage  126 , between a first or retracted position, shown in FIGS. 6 and 7, and a second or extended position, shown in FIGS. 8 and 9. Preferably, the sliding member  124  is fitted with one or more interconnected slots  128 , which engage corresponding dowel pins  130  within the passage  126 , providing a releasable engagement in the first and second positions. A spring  131  is retained between a pair of floating washers  133  by a bolt  135  threaded into the base of the sliding member  124 . The floating washers  133  engage one or more dowel pins  130  in the extended and retracted positions of the sliding member  124 , providing a resilient retaining force. 
     Those of ordinary skill in the art will recognize that the slots  128  and dowel pins  130  may be replaced by any suitable elements configured to provide a releasable engagement for the sliding member  124  within the passage  126 . For example, the sliding member  124  may be adapted for unimpeded motion along the length of passage  126 , and to be secured in place with one or more conventional set screws (not shown) disposed in extension arm  109 . 
     It is also possible that other components may be used to create an extendable arm, and as such, the above description is not meant to be limiting. For example the round members may be replaced by flat or rectangular members without compromising the function of the device. 
     As best seen in FIG. 8, roller head  110  is conventional in design, and preferably consists of a support  132  secured to the sliding member  124 , a roller  134 , and an optional imbalance correction weight holder  136 . The roller  134  is disposed on a shoulder screw  138  which is secured within the support  132  for rotational movement about a longitudinal axis RA parallel to the axis SA of shaft  102 . One or more bearings  140 , retainer rings  141 , and wave springs  142  facilitate the rotational movement of the roller  134  and shaft  138  relative to the roller head  110 . 
     Roller  134  is configured to contact an inner surface of a wheel rim  14  during rotational movement of the wheel rim  14 . Accordingly, the dimensions of the roller  134 , and the geometry of the rim contact arm  104  in general, must be known to a predetermined tolerance, permitting the wheel balancer or vibration control system  60  to identify a wheel rim radius based on a measured rotational position of the rim contact arm  104  about the shaft  102 , when the roller  134  is in contact with the wheel rim  14 . 
     The optional imbalance correction weight holder  136  disposed on the roller head  110  is conventional in design, and preferably includes an imbalance correction weight clamp  144  adapted for sliding movement within a channel  146  in a spring housing  148  seated on a weight lever  149 . A resilient member  150 , such as a coil spring, provides an engaging force on the imbalance correction weight clamp  144 . The imbalance correction weight holder  136  is secured to the support  132  by a retainer  151  and a shoulder screw  153 . 
     During use, the imbalance correction weight clip  144  is displaced within the channel  146 , compressing the resilient member  150 , and an imbalance correction weight (not shown) is seated on the weight clip  144 . The resilient member  150  urges the weight clip  144 , and the seated imbalance correction weight, into engagement against an edge of the roller  134 , releasably securing the imbalance correction weight. The roller head  110  is moved into position adjacent a predetermined point on a wheel rim  14 , and the imbalance correction weight is transferred from the weight clip  144  to the wheel rim  14  in a conventional manner. Those of ordinary skill in the art will recognize that a variety of mechanical configurations may be utilized in the imbalance correction weight hold  136  to releasably hold an imbalance correction weight for delivery to the surface of a wheel rim  14 . 
     As seen in FIG. 10, during use, the rim contact arm  104  can rotate about the wheel data acquisition arm shaft  102  between a maximum outward position P max , and a minimum inward position P min . Rotation of the rim contact arm  104  past the maximum outward position P max  reduces the distance between the rim contact arm  104  contact point on the wheel rim  14  and the axis of rotation for the wheel rim about the balancer shaft  42 . Correspondingly, the minimum inward rotational position P min  is defined as the point at which the rim contact arm  104  swing is blocked from further rotation by the balancer shaft or spindle  42  upon which the wheel rim  14  is mounted. As can be further seen in FIG. 10, use of the rim contact arm  104  with the sliding member  124  in a first or retracted position permits use with wheel rims  14  having a first range if diameters, R min1  to R max1 . 
     Extending the sliding member  124  to a second or extended position permits use with wheel rims  14  having a second range of diameters, R min2  to R max2 , where R min2 &gt;R min1  and R mas2 &gt;R max1 . For example, with the sliding member  124  in the first or retracted position, R min1 =5″ and R max1 =11″ and with the sliding member  124  in the second or extended position, R min2 =11″ and R max2 =15″. Those of ordinary skill in the art will recognize that the length of sliding member  124  may be selected based upon the desired extension range for the rim contact arm  104 , and that alternate sliding members  124  having differing lengths may exchanged as required to achieve the desired extension range for wheel rims  14  of varying sizes. 
     In one embodiment, an operator provides an indication to the central processing unit  32  of the wheel balancer  60  as to the extension of the sliding member  124 . Alternatively, as is shown in FIG. 11, a position sensor  160  is associated with the rim contact arm  104 , in addition to displacement sensor  68  and rotation sensor  70 . Position sensor  160  is configured to provide a signal to the central processing unit  32  of the wheel balancer system which is representative of the extension of the sliding member  124 . 
     For example, position sensor  160  may consist of a mechanical switch disposed in operative relationship to the sliding member  124 , such that displacement of the sliding member from the first or retracted position to the second or extended position toggles the mechanical switch between a first and second state. Corresponding electrical signals from the mechanical switch are transmitted to the central processing unit  32  through associated wires or other conventional electrical circuits. 
     Those of ordinary skill in the art will recognize that the position sensor  160  may consist of any of a variety of conventional electrical, mechanical or optical position detection apparatus. For example, an LVDT or potentiometer circuit may be operatively coupled to the sliding member  124  to generate a signal proportional to the position of the sliding member  124  relative to the passage  126 , or an optical sensor may be disposed to view one or more gradient markings on the sliding member  124 , or to obtain one or more images indicative of the position of the sliding member  124 . An ultrasonic sensor may be used to sense the position of the sliding member as well. 
     In an optional embodiment, shown in FIG. 12, the requirements for both operator positional input or a position sensor  160  are eliminated by mounting the roller  134  on the roller head  110  such that the roller rotational axis RA is displaced in a predetermined manner from the axis of shaft  138 . When the roller  134  is brought into contact with the wheel rim  14 , and the wheel rim  14  driven through at least one complete rotation, the eccentric mounting of the roller  134  will cause a high-frequency cyclical variation in the rotational position of the wheel data acquisition arm  104 . 
     As shown in FIG. 13, this high-frequency cyclical variation is readily detectable in the signal from the rotational position sensor  70  operatively coupled to the shaft  102 . For purposes of the example shown in FIG. 13, rim runout is assumed to be zero. As wheel rim  14  rotates through a 360° revolution, the radius of the wheel at the point of contact with the roller  134  remains essential constant, as represented by the circle with radius R r . However, the radial distance from the axis of rotation of the wheel rim  14  to the axis of rotation of roller  134  will vary in a sinusoidal pattern, as shown by R s  in FIG.  13 . Since the amplitude of the sinusoidal pattern is known, based on the eccentric mounting of the roller  134 , and the frequency of the sinusoidal pattern is known to be significantly higher than that induced by any runout or wheel rim deviations, the effect of this sinusoidal pattern can be subsequently filtered from the signal generated by the shaft rotational position sensor  70 , permitting rim runout measurements to be obtained. 
     The signal from the rotational position sensor  70  is analyzed using Fast Fourier Transform analysis, or another suitable signal analysis process, by the central processing unit  32  to either identify the number or rotations or cycles of the roller  134  for each complete rotation of the vehicle wheel rim, or the first harmonic frequency of the cyclical variation. The central processing unit  32  is further configured to use this information, together with the known dimensions of the roller  134  and the signal indicating the actual rotational position of the wheel data acquisition arm shaft  102 , to determine the radius of wheel rim  14 . In addition, the central processing unit  32  is configured to identify if the sliding member  124  is in the first or retracted position, or the second or extended position, based upon the same information and the known geometry of the wheel balancer system  60  and wheel data acquisition arm  100 . 
     For example, if there is no overlap in the range of wheel rim diameters which are contacted by the roller  134  in the first or retracted position and in the second or extended position, then identification of the wheel rim diameter from the sinusoidal signal generated by the roller  134  provides a positive identification of the position of the sliding member  124 . If, however, there is a degree of overlap between the two ranges of wheel rim diameters, such as shown in FIG. 10, the simple geometry of the wheel balancer  60  and the wheel data acquisition arm  100  dictates a known correlation between the rotational position of the wheel data acquisition arm shaft  102  known from sensor  70 , the determined wheel rim diameter, and the unknown position of the sliding member  124 , permitting the central processing unit  32  to identify the correct position. 
     In an alternate embodiment suitable for use with wheel balancer or wheel vibration control systems including a second, outer wheel data acquisition arm  61  and an associated roller or ball  63 , an approximate wheel rim diameter measurement is directly obtained. The outer wheel data acquisition arm  61  is moved such that the roller or ball  63  is brought into contact with the outer wheel rim lip  18 . Using a rotational position sensor (not shown) coupled to the outer wheel data acquisition arm  61 , an approximate wheel rim diameter at the contact point of the roller or ball  63  may be obtained from the measured rotational position and known geometry of the outer wheel data acquisition arm  61 . The approximate wheel rim diameter is utilized, as previously described, by the central processing unit  32  to identify if the sliding member  124  is in the first or retracted position, or in the second or extended position, based upon the known geometry of the wheel balancer system  60  and wheel data acquisition arm  100 . 
     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained. As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.