Abstract:
A wheel inflation apparatus including a wheel engagement unit that suspends a tire/wheel assembly and at least one inflation unit coupled to the robotic arm, each inflation unit being configured to inflate the tire/wheel assembly. A load measuring unit is configured to sense an amount of load being applied to the wheel/tire assembly. A controller is coupled to the load measuring unit for receiving a load signal and determining an internal air pressure of the tire/wheel assembly based on the load signal. The controller controls the at least one inflation unit based on the determined internal air pressure and a target (desired) air pressure value.

Description:
RELATED APPLICATION 
       [0001]    This U.S. patent application claims priority to U.S. Provisional Application 61/865,368 filed on Aug. 13, 2013. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to an apparatus and method for inflating a wheel/tire assembly with reactive tire pressure monitoring. 
       BACKGROUND 
       [0003]    A wheel/tire assembly can be assembled as part of automated process. During assembly, a robot can move a wheel to a mounting station, where the wheel is mounted onto the tire. The robot can also move the wheel with the tire mounted thereon, to an inflation station, where the wheel/tire assembly is inflated. The wheel/tire assembly can then be moved to a balancing station where the wheel/tire assembly is balanced. Each step takes time to perform and each station takes space in an assembly plant. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0004]      FIGS. 1A ,  1 B and  1 C are schematic drawings illustrating example components of an inflator with reactive tire pressure monitoring. 
           [0005]      FIG. 2  is a flow chart illustrating an example set of operations for a method for operating a reactive tire pressure device. 
           [0006]      FIG. 3  is an enlargement showing the interaction of the inflation probe with its environment during the inflation process. 
           [0007]      FIG. 4  is a schematic drawing of the force created during the inflation process and how those forces result on the strain sensed by load cell. 
       
    
    
       [0008]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0009]      FIG. 1A  illustrates an example robotic inflator with reactive tire pressure mounting  10 . According to some implementations, the inflator  10  includes a wheel engagement unit  12 , a load cell  14 , one or more inflation units  16 , a cylinder  24 , a cylinder rod  26 , and a controller  30 . The inflator  10  can include additional or alternative components. 
         [0010]    The wheel engagement unit  12  is configured to engage a wheel  42  of a wheel/tire assembly  40 . A tire  44  is mounted onto the wheel  42  at a first station. The first station may be at a first location, or the first station (as well as other stations) may be movable with respect to the wheel/tire assembly  40  and the wheel engagement unit  12 . Prior to or after the tire  44  is mounted onto the wheel  42 , the wheel engagement unit  12  engages the wheel  42 . In some implementations, the wheel engagement unit  12  includes one or more mechanisms  13  that are inserted into the center hub and/or the lug-nut holes. The wheel engagement unit  12  may include alternative or additional means for engaging the wheel  42 . For example, the wheel engagement unit  12  may include magnetized screws or pins that are inserted into the center hub and/or the lug-nut holes or a magnetized surface that attracts the center hub. The engagement unit  12  is capable of grabbing and lifting the tire/wheel assembly  40  away from platform  11 . 
         [0011]    Each inflation unit  16  is configured to inflate the wheel/tire assembly  40 . In the illustrated example, the inflator  10  may include two inflation units  16 ,  16 ′. It is noted, however, that the inflator can include a single inflation unit  16  or more than two inflation units  16 ,  16 ′ as well. In some implementations, an inflation unit  16  includes an inflation probe  18  (which is connected to a compressed air source such as an air compressor  19  or similar device) a probe stirrup  20 , an inflator actuator  22  and a stirrup actuator  23 . The probe stirrup  20  can include a cavity  21  that is larger in at least one dimension than the inflation probe  18  thereby permitting the inflation probe  18  to pass freely through the cavity  21 . The probe stirrup  20  can be made of a rigid material (e.g., steel) that can withstand the force of the tire  44  forcibly abutting the portion of the probe stirrup  20  forming the cavity. In operation, a stirrup actuator  23  can linearly actuate a probe stirrup  20  at least along one axis into the tire/wheel assembly  40 , such that the probe stirrup  20  is inserted in the gap between the wheel  42  and the tire bead  46  of the tire  44 .  FIG. 1B  illustrates an example where the probe stirrup  20  has been inserted (by actuator  23 ) between the wheel and the sidewall  46  of the tire  44 . Prior to the inflation of the wheel/tire assembly  40 , the probe stirrup  20  can be easily placed in between the tire bead  46  and the wheel  42 . Thereafter, the inflator actuator  22  manipulates the inflation probe  18  through the cavity of the probe stirrup  20 . In this way, the probe stirrup  20  prevents the inflation probe  18  from being pinched between the wheel  42  and the tire bead as a result of the increasing internal air pressure of the tire  44  during inflation.  FIG. 1C  illustrates an example of the inflation probe  18  being located in the cavity of the probe stirrup  20 . Once the inflation probe  18  is inserted into the cavity of the probe stirrup  20 , the air compressor (not shown) can be commanded to begin pumping air into the wheel/tire assembly  40 . 
         [0012]    Now referring to  FIG. 4 , the load cell  14  outputs an electrical signal along conductor  15  indicating a measure of strain that is sensed across load cell  14  (i.e. F′ A +F′ B ). The amount of strain that is sensed corresponds, in part, to the force F′ A  (exerted by the tire  44  against probe  18 ,  18 ′ and probe stirrup  20 ,  20 ′) and force F′  B  (exerted by the tire  44  against lower wheel bead  41 ,  41 ′ of wheel  42 . The force exerted by the tire against  18 ,  18 ′,  20 ,  20 ′,  41 ,  41 ′ is, at least in part, a function of the internal air pressure within wheel/tire assembly  40 . In some implementations, the internal air pressure within cavity  45  of the wheel/tire assembly  40  results in an upward force being applied to the inflation probe  18  and/or the probe stirrup  20  as the wheel/tire assembly  40  is inflated. In these implementations, the upward force is transferred to the load cell  14  via rigid support structure  21 ,  21 ′. In some implementations, the upward force F′ A  may be transferred to the load cell  14  by way of the cylinder  24 , which transfers the upward force to the cylinder rod  26 . The cylinder rod  26  can transfer the upward force to the load cell  14 . Additionally or alternatively, the air pressure within air cavity  45  of the wheel/tire assembly  40  may result in a downward force F′ B  being applied to the wheel/tire assembly  40  as the wheel/tire assembly  40  is inflated. The downward force is transferred to the wheel engagement unit  12 , which in turn transfers the downward force onto the load cell  14 . In this way, as the inflation probe  18  inflates the wheel/tire assembly  40 , the upward force and the downward force act simultaneously on the load cell  14 . The arrows  50  and  52  depicted  FIG. 1C  are examples of the forces acting upon the load cell  14 . The load cell  14  outputs a signal indicating a magnitude of the force. In an embodiment, inflation units  16 , and  16 ′ are spaced apart from and do not contact any part of wheel  42 . This spaced relationship (gap) enhances the accuracy of the system by eliminating any of the reaction force F AN  from being drawn away from load cell  14 . In an embodiment, during the inflation process, wheel engagement unit  12  is the sole means of supporting tire/wheel assembly  40  (i.e. platform  11  does not engage assembly  40 ). 
         [0013]    The load cell  14  can measure the magnitude in any suitable manner. In some implementations, the load cell  14  includes a strain gauge that measures the magnitude of the force based on a change of resistance of a resistor when a force is applied and distorts the resistor. Additionally or alternatively, the load cell  14  can be a hydraulic load cell that measures the magnitude of the force based on a displacement of a liquid caused by the upward and downward forces acting upon the load cell. 
         [0014]    The controller  30  can be a one or more processors, microprocessors, and/or ASIC circuits that control operation of the inflator  10 . In some implementations, the controller  30  executes machine-readable instructions for controlling the inflator  10 . The controller  30  can control actuators and/or motors that cause the motion of the wheel engagement unit  12 , the inflation unit  16 , the cylinder rod  24 , and the cylinder. Furthermore, the controller  30  can determine the internal air pressure of the wheel/tire assembly  40  based on the output signal  15  of the load cell  14 . In some implementations, the controller  30  determines the air pressure based on a lookup table. The look table can be generated heuristically, such that air pressure values can be correlated to various combinations of force measurements and/or tire parameters (e.g., tread type, tire type, wheel size). Additionally or alternatively, the air pressure can be determined according to a predetermined equation where air pressure is a function of the force measurement and, possibly, one or more tire parameters. When the internal air pressure reaches a threshold, e.g., 32 psi, the controller  30  commands the inflation unit  16  to withdraw from the wheel/tire assembly  16 . 
         [0015]    In some implementations, the cylinder  24  mechanically moves the inflator  10  from a first position to a second position. The movement of the cylinder  24  can be controlled by one or more actuators or motors that move the cylinder  24  in one or more directions. For example, the cylinder  24  can be controlled by an actuator or motor to move the inflator  10  from a tire mounting station to a wheel balancing station. At the control of the actuator or motor, the cylinder  24  can raise and lower the wheel engagement unit  12  and can also move the wheel engagement unit  12  horizontally. In some implementations, the wheel/tire assembly  40  is inflated while the cylinder  24  is moving the wheel/tire assembly  40  from the first location to the second location. 
         [0016]    Additionally or alternatively, the cylinder  24  raises the wheel/tire assembly  40  and various stations (e.g., wheel mounting and wheel balancing stations) are moved to the location of the wheel/tire assembly  40 . In these implementations, the inflation unit  16  inflates the wheel/tire assembly  40  while the cylinder  24  is raising the wheel/tire assembly  40 . 
         [0017]    In some implementations, the cylinder rod  26  raises and lowers the wheel engagement unit  12 . Furthermore, in some implementations, the cylinder rod also rotates the wheel engagement unit  12  to engage the hub and/or the lug-nut holes. The movement of the cylinder rod  26  can be controlled by one or more actuators and/or motors. 
         [0018]    The inflator  10  of  FIG. 1  is provided for example only. Alternate configurations of the inflator  10  are contemplated and are within the scope of the disclosure. For instance, the inflation unit  16  may be configured to inflate the wheel/tire assembly  40  via an inflation valve (not shown) disposed along the wheel  42  or tire  44 . In these implementations, the load cell  14  would operate in substantially the same manner, but the upward force would be transferred from the inflation valve. 
         [0019]      FIG. 2  illustrates an example set of operations that can be performed by the controller  30  according to some implementations of the present disclosure. It is noted that in alternate configurations of the inflator  10 , the operations may be varied accordingly. 
         [0020]    At operation  210 , the controller  30  commands an actuator or motor connected to the cylinder  24  to move the cylinder to a first location. The first location may be a station on an assembly line of the wheel/tire assembly (e.g., a tire mounting station). 
         [0021]    At operation  212 , the controller  30  causes the wheel engagement unit  12  to engage the wheel/tire assembly  40 . The controller  30  can command the actuator and/or motor connected to the cylinder rod  26  to move the wheel engagement unit  12  into position to engage the wheel/tire assembly  40 . Once the wheel engagement unit  12  is in position to engage the wheel/tire assembly  40 , the controller  30  can command the actuator and/or motor connected to the cylinder rod to move the wheel engagement unit  12  into an engaged position (e.g., rotate the wheel engagement unit  12  such that the wheel/tire assembly  40  is mounted onto the wheel engagement unit  12 ). 
         [0022]    At operation  214 , the controller  30  causes the cylinder to begin moving the wheel/tire assembly  40  from the first location to a second location. The second location can be another station on the assembly line, such as a wheel balancing station. The controller  30  can move the wheel/tire assembly  40  by, for example, commanding an actuator or motor connected to the cylinder  24  to move the cylinder in a direction of the second location. 
         [0023]    At operation  216 , the controller  30  causes the inflation probe  18  to be inserted into the wheel/tire assembly  42 . In some implementations, the controller  30  commands the stirrup actuator  23  to slide the probe stirrup  20  into a position between the wheel  42  and the tire  44  (i.e., at the side wall  46  of the tire  44 ). Once the probe stirrup  20  is in position, the controller  30  commands the inflator actuator  22  to move the inflation probe  18  into the cavity of the probe stirrup  20 . Once, the inflation probe  18  is in the cavity of the probe stirrup  20 , the inflation probe  18  is in position to inflate the tire. The foregoing operation can be performed for each inflation unit  16 .  FIG. 3  illustrates an example of the inflation probe  18  being in position to inflate the wheel/tire assembly  40 . As illustrated, a distal end  300  of the inflation probe  18  is disposed in the cavity  302  of the probe stirrup  20 . At operation  218 , the controller  30  commands the air compressor  19  to inflate the wheel/tire assembly  40 . 
         [0024]    At operation  220 , the controller  30  can determine an air pressure in the wheel/tire assembly  40 . In some implementations, the controller  30  receives the air pressure measure from the controller  30 . In some implementations, the controller  30  receives a signal indicating the force being applied to the load cell  14  and calculates the air pressure based on the signal. The controller  30  can calculate the air pressure according to a lookup table or a predetermined equation. 
         [0025]    At operation  222 , the controller  30  determines whether the determined air pressure is less than a threshold. The threshold is indicative of a desired air pressure in the wheel/tire assembly  40 . If the air pressure is less than the threshold, the controller  30  continues to command the air compressor  19  to inflate the wheel/tire assembly  40 . Otherwise, when the air pressure equals or exceeds the threshold, the controller  30  causes the inflation probe  18  to be removed from the wheel/tire assembly, as shown at operation  224 . In some implementations, the controller  30  commands the inflation actuator  22  to retract the inflation probe  16  and then commands the probe actuator  23  to retract the probe stirrup  20 . At operation  226 , the movement of the wheel/tire assembly  40  to the second location is completed. The controller  30  can continue to command the actuator or motor of the cylinder  24  to move the cylinder  24  until the wheel/tire assembly  40  reaches the second location. The controller  30  may further command the wheel engagement unit  12  to disengage the wheel/tire assembly  42 . 
         [0026]    Variations of the method  200  are contemplated and are within the scope of the disclosure. Furthermore, depending on the assembly of the inflator  10  (e.g., whether the wheel/tire assembly  10  is moved from a first station to a second station or whether the first station and the second station are movable with respect to the wheel/tire assembly  40 ), some operations may be varied, replaced, or removed.