JP2011107163A - Vibration correction system for tire testing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for improving the measurement of force variation in a tire to be tested with tire uniformity measurement apparatus. <P>SOLUTION: This apparatus includes a load wheel assembly including a load wheel, connected to a load sensor for detecting the force applied to the load wheel by a tire to be tested. To detect the vibration of the load wheel by any other force than the one applied by the tire, the vibration sensor is linked to the load wheel assembly. To provide more accurate uniformity data of a tire, there is provided a means of subtracting a force induced by vibration from the force applied by the tire. A vibration sensor composed of an accelerometer is used to determine the force causing vibration in the lateral and radial directions with respect to the load wheel. A signal obtained by the accelerometer is transmitted to a differential amplifier which accepts a signal from the load cell in the same way. All signals indicate more accurately an actual vibrating force generated by a tire to be tested. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides more accurate tire uniformity data so that more or less tire irregularities detected in the tire can be corrected more accurately in the tire test, particularly measuring tire uniformity. The present invention relates to an improved method and apparatus for obtaining.

  In the manufacture of tires, tires can have various irregularities and dimensional variations. For example, dimensional irregularities can result from inaccuracies in the molding process, changes in the properties of materials and compounds employed in manufacturing tires, inaccurate centering and variations in the vulcanization process, etc. . All tire irregularities and variations that can occur during manufacturing, whether alone or by interaction, are all eccentric, tire dynamic and static imbalances, and tire vibration in use. And can cause force fluctuations that can cause noise.

  Many of these irregularities can be corrected by first measuring tire variations and applying various corrective actions to the tire. In order to measure the variation, the tire is placed on a tire uniformity tester. In currently available tire uniformity machines, the test is completely automatic. The tires are sent to a test bench by a conveyor, where each tire is attached to a chuck, inflated to a predetermined pressure, and rotated at a standard speed so that its tread surface is in contact with the peripheral surface of the road wheel. Driven. The road wheel includes a load cell that measures a force generated by a tire acting on the road wheel. The data collected during the testing process is taken from shoulder and tread grinders that selectively polish rubber from various areas of the tire to define tire grades and / or to compensate for variations detected during the testing process. Can be used to take corrective action immediately. Alternatively or in addition, data obtained during the test cycle is used to mark specific areas of the tire and alert the installer to areas of concern such as tire irregularities or high strength points This allows the installer to take corrective or corrective actions when attaching the tire to the wheel.

  In a typical tire test system, the road wheel is free to rotate about an axis parallel to the tire's axis of rotation. The spindle at the opposite end of the load wheel comprises a load cell that measures the force acting on the load wheel in the direction of the object to be examined. Accurate measurement of the force exerted by the tire, for example, a grinding device that removes excess tire material to correct irregularities that occur during the manufacturing process, so that the tire uniformity can be accurately determined after the force measurement procedure. It becomes possible to adjust.

  Examples of tire test systems and road wheel structures are described in US Pat. In these systems, the load wheel spindle includes a load cell that is fixed to a movable carriage. The carriage is attached to a ball screw driven by a motor and a gear reduction device. The rotation of the shaft of the screw moves the ball screw and carriage in the direction of the tire under test or in the opposite direction, and the carriage slides along the machine frame. The servo mechanism moves the carriage to the target position based on the force signal generated by the load cell.

  Prior art tire test systems, and particularly the known road wheel assemblies used therein, measure tire uniformity in an acceptable manner, but are deficient and leave room for improvement. The road wheel assembly (road wheel, drive shaft and bearing) is rather heavy. As a result, the load cell receives and reacts to the movement of the entire machine frame as well as the force generated by the rotating tire. Machine frame motion may be caused by internal vibrations such as external vibrations such as vibrations caused by traffic on industrial trucks near the machine or vibrations caused by the operation of tire conveyors or grinders that form part of the inspection machine There is.

  The forces generated by these extraneous vibrations are undesirable and are error in the measurement system. In prior art devices, the tire inspector is placed on a high-mass foundation, or alternatively the machine is arranged to avoid actuation or movement of the machine subassembly (such as a grinder) while measurements are being made By trying to avoid the above error. Such prior art methods significantly increase the cost of installation and increase operating costs due to increased cycle times and reduced machine throughput.

US Pat. No. 6,016,695 US Pat. No. 5,793,231 US Pat. No. 5,992,227

  The present invention provides an improved method and apparatus for obtaining tire uniformity data to be tested in a tire uniformity machine. In the preferred embodiment illustrated, the apparatus includes a road wheel assembly that includes a rotatable road wheel. A load sensor or load cell for detecting the force applied to the load wheel by the tire under test forms part of this assembly.

  A vibration sensor for detecting the vibration of the road wheel is also provided. The vibrations to be monitored are generally caused by movements in the machine frame caused by the movement of industrial lift trucks near the machine or the movement of components such as conveyors or grinders inside the machine. The signal or information obtained from the vibration sensor is subtracted from the entire signal or data generated by the load cell to obtain more accurate tire uniformity data.

  The disclosed apparatus reduces or eliminates errors that are sometimes caused in tire uniformity data measurements due to extraneous forces or vibrations experienced by the load cell during tire testing.

  In a preferred embodiment, the vibration sensor comprises an accelerometer that is mounted on a road wheel assembly. In the illustrated embodiment, at least two accelerometers are used, one for detecting lateral force components and one for detecting radial force components. In a more desirable construction of the illustrated embodiment, two radial accelerometers are not installed because a single radial accelerometer cannot be installed in line with the radial plane of the road wheel assembly for existing components. used. As a result, two symmetrically spaced radial accelerometers are used.

  In the illustrated embodiment, the signal generated by the accelerometer is communicated to the differential amplifier through an adjustment circuit and a counting circuit. The conversion factor used by the counting circuit is determined by the characteristics of the accelerometer used. A signal from the load cell representing the total force applied to the load wheel is also transmitted to the differential amplifier. The overall force includes both the force generated by the tire under test and the force generated by the vibration applied to the tire inspection machine. As a result, the net signal obtained from the differential amplifier more accurately reflects the actual tire uniformity data of the tire being measured.

  Additional features of the present invention will become apparent and will be better understood when the following detailed description is read in conjunction with the accompanying drawings.

1 is a fragmentary side view of a tire test bench and road wheel assembly constructed in accordance with a preferred embodiment of the present invention. FIG. 1 is a fragmentary view of a road wheel assembly, partly in cross-section. FIG. 3 is a top view of the load wheel assembly shown in FIG. It is a block diagram which shows the data acquisition method which correct | amends the lateral force or lateral vibration error given to a test stand or a load wheel. It is a block diagram which shows the data acquisition method which correct | amends radial force or radial vibration error. 1 is a cross-sectional view of a road wheel configured according to a preferred embodiment of the present invention.

  FIG. 1 shows the overall arrangement of a tire uniformity tester including a device for reducing the effect of vibration errors on the measurement of the force applied to the tire under test. The entire tire uniformity tester is described in more detail in US Pat. No. 6,057,059 entitled “Tire Uniformity Test System”, the contents of which are incorporated herein by reference.

  Referring to FIG. 1, the tire test system includes a test bench 12, where the tire is tested and optionally adjusted to adjust tire roundness, mechanical uniformity and / or other physical characteristics. Polished. In FIG. 1, the tire indicated by reference numeral 20 (shown by a dotted line) is tested by an appropriate conveyor such as the conveyor disclosed in Patent Document 1 above so as to be pressed between the upper and lower rims of the chuck device. Sent to stand 12. The rims 24 and 26 form part of the spindle assembly 410 and the movable chuck assembly 310, respectively. The chuck device comprises a tire width adjustment chuck device for a tire test system disclosed in Patent Document 3 entitled “Automatic width adjustment chuck device for tire test system” (the contents of which are incorporated herein by reference). Can do.

  The tire is pressed between the rims 24, 26 and inflated through a chuck device. After inflation, the road wheel 510 that forms part of the road wheel assembly 500 is moved to contact the outer surface of the tire 20. As before, the tire is rotated against the load wheel 510 and the load wheel monitors the load applied by the tire through the load cells 530,540. As is known in the art, data obtained from the load cell is used to determine tire uniformity. If desired, adjustment of tire uniformity is typically performed by one or more grinders (shown in dotted lines) indicated by reference numerals 50,52.

  The tire test system includes a probe system, generally indicated by reference numeral 56. A probe system suitable for use in the illustrated tire test system is disclosed in detail in US Pat. No. 6,057,059 above entitled “Tire Uniformity Test System”, the contents of which are hereby incorporated herein by reference. It has been incorporated.

  The load wheel assembly 500 can have a variety of configurations. An example of a suitable road wheel assembly is disclosed in US Pat. Referring to FIG. 2, the road wheel assembly 500 includes three main components: a road wheel 510, a C-shaped carriage 550, and a drive mechanism 600. The illustrated road wheel includes a cylindrical outer wall 512, the exterior of which contacts a rotating tire held by a chuck assembly, as is known in the art. The outer wall 512 of the load wheel 510 is connected to a hub 514 that forms a hollow hole 520. Hub 514 is joined to outer wall 512 by a plurality of solid annular disks 516,518. In the illustrated road wheel embodiment, the disk 516 is disposed between the hub and the outer wall near both ends of the hub 514 and outer wall 512 to seal the hollow interior of the road wheel, whereas the disk 518 is The central portion of the hub 514 and the central portion of the outer wall 512 are disposed. Further details of the illustrated road wheel are given in US Pat.

  With particular reference to FIGS. 2 and 3, the C-shaped carriage 550 is shown to include an upper horizontal leg 552, a lower horizontal leg 554, and a vertical connecting leg 556 extending therebetween. The ends 553, 555 of the carriage legs 552, 554 are shaped to include steps or recesses that are attached (or alternatively molded integrally) to the mounting pads 558, 560. The pads 558, 560 are equipped with spindle ends 522, 524 and load cells 530, 540 of the load wheel spindle 521.

  As shown in FIG. 2, the C-shaped frame 552 is supported so as to slide on the base 62a. A drive mechanism 600 (see FIG. 3) mounted on the vertical frame components 68a, 68b affects the movement of the carriage 552 toward and away from the tires located on the test bench. The drive mechanism includes a ball screw 640 that is operatively connected to the radial center of the road wheel frame 552. Details of the drive mechanism 600 are shown in Patent Document 2. The disclosed tire uniformity tester includes a data acquisition device that corrects extraneous vibrations and / or forces transmitted to the load cells 530, 540 that would otherwise cause errors in the measurement system. This extraneous vibration can occur as a result of movement of equipment near the tire test system, and the tire test table itself, such as the operation of grinders 52, 54 or the operation of various conveyors (not shown) May be the result of the movement of a component that forms part of.

  The present invention greatly reduces the effects of this type of extraneous vibration on the measurement of tire force fluctuations on the test bench 12. In accordance with a preferred embodiment of the present invention, the apparatus comprises one or more transducers or other sensors that measure or monitor tire inspection machine vibrations for acceleration. The system may also include a scaling mechanism that adjusts the output of the vibration measurement transducer / sensor to accurately represent the force generated by acceleration according to Newton's law of motion (F = ma). These forces, which are derived from the measured vibrations and would otherwise produce error or false data, are subtracted from the combination of vibration induced forces and tire uniformity forces measured by the load cells 530,540. The result is data that more accurately represents the actual force variation of the tire.

  With reference to FIGS. 1 and 2, the vibration compensator includes an acceleration transducer that is strategically mounted to the road wheel assembly 500. In the illustrated embodiment, the two components of vibration force are monitored separately. In general, tire uniformity machines measure “radial” and “lateral” forces. In a tire test, the term “lateral” is defined to mean a force along the axis of rotation of the tire that is transverse to the tire when attached to a vehicle. In the tire inspection machine shown in FIGS. 1 and 2, since the tire is placed horizontally during the test, the “lateral force” is actually the vertical direction in FIGS. In other words, the lateral force component acts along a vector parallel to the axis of rotation of the tire itself (indicated by reference numeral 688 in FIG. 1). The radial component is defined to be along the axis connecting the rotation center of the tire and the road wheel, and is parallel to the horizontal direction, that is, the rotation plane of the tire.

  The lateral component of the vibration is detected by an accelerometer 700 provided on or near the rotation axis 698 of the road wheel 510. Since it is not possible to mount the accelerometer accurately on the rotation axis of the load wheel 510 in the illustrated configuration, the actual equipment position of the lateral accelerometer 700 is shifted to one side of the axis as seen in FIG. ing.

  The radial component of the force is detected by at least one accelerometer 702 provided on the C-shaped cartridge 552 of the load wheel assembly 500. In the illustrated example, the cartridge drive mechanism 600 is attached to the C-shaped cartridge at its axial center. This makes it impossible for the accelerometer 702 to be disposed in line with the rotation center plane indicated by the one-dot chain line 706 of the load wheel 510. Thus, a pair of accelerometers 702, 704 are located on either side of the center plane and are spaced symmetrically about the axis to detect force with the required sensitivity.

  In order to detect accurately, it must be noted that it is important for the accelerometer to measure the same direction of movement, where the overall movement affects the force measurement at the load cell. In particular, the uniformity measuring device is designed with high sensitivity to the indicated force and low sensitivity to the corresponding moment. If possible, a transducer for measuring acceleration should be provided on a predetermined measuring direction, i.e. a lateral or radial line, passing through the center of gravity of the road wheel assembly. In some cases, this may not be possible because there is no suitable mounting surface, as in the embodiment shown in FIG. In these cases, two transducers spaced symmetrically about the axis may be used to obtain the required sensitivity to the force while keeping the moment sensitivity low.

  It should be noted that in some cases it is desirable to measure the moment with a uniformity measuring device. In those cases, symmetrically spaced acceleration transducers are used connected to detect the moment difference about the axis.

  In the preferred embodiment shown, the acceleration transducers 700, 702, 704 form part of a uniformity measurement device such as that disclosed in the previously described '480 patent. In the illustrated system, the load wheel has a weight of about 340 pounds. Two biaxial load cells 530, 540 are used to measure radial and lateral forces. The illustrated example load cell is a Ribau 6443-105 model with a measuring range of 500 pounds in the lateral direction and 2000 pounds in the radial direction. These load cells are added to a measurement range of 1000 lbs (about 460 kgw) in the lateral direction and 4000 lbs (about 1820 kgw) in the radial direction.

  The signal from the load cell is processed by an Akron standard instrument amplifier card 440-0027-XX modified as shown in FIGS. As can be seen in FIG. 4, the lateral channel contains signals from load cells 530, 540, amplified (by amplifier 709), and fed to differential amplifier 710. The signal from accelerometer 700 is adjusted (by adjustment circuit 712) and expanded (by 1.36 times) by counting circuit 714 to yield a total signal representing the actual force variation measured on the tire being tested. The output is similarly supplied to the differential amplifier 710.

  Referring now to FIG. 5, the lateral channel includes signals received from load cells 530, 540 and transmitted via amplifier 718 to another differential amplifier 716. Information regarding acceleration is transmitted to the differential amplifier 716 by the accelerometers 702 and 704. These signals are adjusted (by the adjustment circuit 720, 722), reduced (by the counting circuit 724), then summed with the load cell data to produce data that does not contain radial force data generated by error oscillations. Is done.

  The acceleration transducer shown as PCB393A03 type vibration accelerometer gave satisfactory results. A signal conditioning circuit known as PCB482A16 type was used. Transducers 700, 702, 704 and signal conditioning circuits 720, 722 are available from PCB Piezotronic, Inc., DePu, NY. As described above, the accelerometer 700 for measuring laterally unrelated forces is provided on top of the load cartridge 552 substantially directly above the center of gravity of the load wheel 510. The radial accelerometers 702, 704 are symmetrically loaded directly above and below the center of gravity of the load wheel because the ball screw 640 (see FIG. 2) that moves the load wheel cartridge is located at the radial center line. It is attached to the wheel.

  As described above, the signals from the accelerometers 700, 702, 704 are scaled by the counting circuits 714, 724. The actual scaling factor of the accelerometer used, such as accelerometer 700, is determined by the accelerometer itself. The methodology for reaching the appropriate scaling factor is described below. In particular, the expansion factor of 1.36 in FIG. 4 of the accelerometer 700 described above was derived as follows. An expansion factor K4 equal to 1.36 of the accelerometer 700 is thus used in the counting circuit 714.

  One skilled in the art will appreciate that the above methodology can be used to calculate an appropriate scaling factor when alternative accelerometers are used. Similarly, it will be well known to those skilled in the art how to use the same methodology to arrive at the radial accelerometer of 0.17 in the illustrated embodiment, ie the accelerometer 702, 704 reduction factor. .

  FIG. 6 shows an alternative embodiment in which the accelerometer is mounted on the road wheel spindle itself. In particular, the road wheel 510 'is rotatably supported by a pair of roller bearings 740, 742 on a fixed axle or spindle 521'. An accelerometer 700 'for measuring lateral force is provided in a center bore 750 formed on the spindle 521'. Signal lead 700a for accelerometer 700 'is supplied from bore 750 to a suitable controller (not shown) including the channel circuit depicted in FIG.

  A single accelerometer 702 'that measures radial force is disposed within a diameter bore 760 formed in the spindle 521'. A signal lead 702a from the radial accelerometer 702 'passes along the outer surface of the axle 730 from the bore 760 and passes through a small crossbore 762 to provide a center bore 750 (provided with a vertical accelerometer 700'). to go into. In the embodiment of FIG. 6, the accelerometers 700 ′, 702 ′ are accurately positioned along the respective lateral and radial directions of the road wheel assembly, such as external forces such as in-factory vehicles, conveyors or grinders. It provides a highly accurate data signal that accurately reflects the lateral and radial accelerations applied to the road wheel assembly by movement of components within the measuring device.

  It will be understood that, although the invention has been described with a certain degree of particularity, various modifications can be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the claims. It must be.

20 tires 500 road wheel assembly 510 road wheel 530 load cell 540 load cell 700 accelerometer 702 accelerometer 704 accelerometer 710 differential amplifier 716 differential amplifier

Claims (11)

An apparatus for improving the measurement of tire force variation tested in a tire uniformity measuring device,
a) a road wheel assembly including a rotatable road wheel;
b) a load sensor for detecting the force imposed on the road wheel by the tire to be tested;
c) one or more accelerometers for detecting vibrations generated in the road wheel by a force other than the force applied by the tire;
d) means for subtracting the force induced by the vibration from the force imposed by the tire so as to obtain more accurate tire uniformity data. i) a counting circuit for scaling the signal generated by the one or more accelerometers;
The apparatus of claim 1, further comprising: ii) means for subtracting the signal from the signal generated by the load cell. a) a road wheel assembly;
b) a tire test section including a tire holding device that holds and rotates the tire;
c) means for rotating the tire in the tire test section;
d) means for contacting the tire with the road wheel;
e) means for measuring the force imposed by the rotating tire on the road wheel;
and f) detecting means for detecting vibration imposed on the road wheel by a force generated by a portion of the tire uniformity measuring device other than the rotating tire. g) The detection The means includes a counting circuit and an accelerometer for scaling the signal generated by the accelerometer in response to the vibration;
h) A tire uniformity measuring apparatus, further comprising differential addition means for adjusting a signal generated by the load cell in order to remove an arbitrary component generated by the vibration. A method for improving the measurement of force fluctuations in a tire uniformity measuring device comprising:
a) providing a road wheel assembly including a road wheel rotatably supported by a frame;
b) providing a load cell connected to the road wheel to detect a force imposed on the road wheel;
c) measuring the acceleration force imposed on the road wheel by an acceleration transducer;
d) subtracting the data obtained by the accelerometer from the entire load cell data to obtain more accurate uniformity data.   5. The method further comprises: scaling the signal generated by the accelerometer; and adding the signal with a differential amplifier to obtain a total signal that does not include data related to the acceleration force. The method described in 1.   The apparatus of claim 1, wherein the road wheel rotates in a plane, and the one or more accelerometers are secured to the road wheel assembly in a plane of rotation of the road wheel.   The apparatus of claim 3, wherein the road wheel rotates in a plane and the accelerometer is secured to the road wheel assembly in a plane of rotation of the road wheel.   The method of claim 4, wherein the road wheel rotates in a plane and the acceleration transducer is secured to the road wheel assembly in a plane of rotation of the road wheel.   The apparatus of claim 1, wherein the one or more accelerometers are secured to a carriage of the road wheel assembly.   The apparatus of claim 3, wherein the accelerometer is secured to a carriage of the load wheel assembly.   The method of claim 4, wherein the acceleration transducer is secured to a carriage of the road wheel assembly.

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