Wheels are inevitably subject to errors due to metal machining. The size of the bead seat is not round, elliptical and square in the radial direction, and there are also twisting characteristics in the axial direction. Therefore, the runout of the wheel is detected to prevent the unqualified wheel from flowing out of the production line. At the same time, the low point of the first harmonic of the radial circle is marked so that the low point of the first round of the radial runout of the wheel is assembled with the high point of the radial force fluctuation (RFV) of the tire to reduce the wheel. Vibration caused by uneven radial force during driving. This paper compares the different matching results of the wheel and the tire. In order to improve the speed and ride comfort, in addition to the good rotation uniformity of the wheel and the tire, the best match between the two is particularly important.
Test principle
The maximum vibration point of the tire identifies the maximum point of longitudinal stiffness of the tire. During the one-turn rotation of the tire, the point at which the vibration is greatest is at the position identified by the maximum vibration point. The tires are rotated one turn on the ground, and the vibration forces they receive at each angle are unequal. This phenomenon is called radial force fluctuation (RFV). When the RFV is too large, the tire generates vibrations that can be perceived by the driver, affecting the driving comfort of the vehicle. Generally, a large tire manufacturer will mark the position of the point on the tire during product inspection. If the vibration value of the tire product is found to be excessive, it will be treated as waste.
The SAE J2133 standard specifies the requirements for the detection of wheel runout and first harmonic. After manually loading the wheel to be tested, the operator selects the measured wheel specification (the technical parameters of the wheel to be tested can be accessed and modified at any time), the inner bead seat The measuring head and the outer bead seat measuring head automatically adjust the position. During the measurement process, the system automatically recognizes whether the measuring position is correct, collects and processes the measured data, and calculates the axial and radial circular runout values ​​and harmonics of the inner and outer bead seat. Wave analysis, display the jitter curve, automatically find the relative position of the maximum jitter value or the minimum jitter value, and automatically judge whether the measurement result is out of tolerance.
Test design
A wheel that pre-measures the radial round runout and the first harmonic value and a tire with a known geometrical inhomogeneity are respectively selected, and after assembling the two, the different positions of the tire relative to the wheel are changed to observe the random matching and The different effects that occur when "smart" matches.
Wheel characteristics
As shown in Fig. 1, the peak value of the radial runout of the test wheel is 3.91 mm, and the first harmonic high point is 1.614 4 mm, which is located at 290° (the valve hole position is 0°).
Figure 1 Wheel bounce and first harmonic
As shown in Fig. 2, the curve shows the non-uniformity of the test tire. The peak value of the radial round jump is 3.12 mm, and the first harmonic low point is 1.246 7 mm, which is located at 100 ° (the valve is the starting position). .
Figure 2 Tire beat and first harmonic
Test results and analysis
The test results of the tire and the wheel at different matching positions are shown in Fig. 3 and Fig. 6.
Figure 3 Initial position random match
Figure 4 tires rotated 90° relative to the wheel
Figure 5 tires rotated 180° relative to the wheel
Figure 6 The tire rotates 270° relative to the wheel
1. Best match
By matching the highest point of the first harmonic of the wheel with the lowest point of the first harmonic of the tire, the best match is obtained by rotating the tire counterclockwise by 170° with respect to the first random matching position of the wheel (see Figure 7).
Figure 7 matches the best possible outcomes
Matching the highest point of the first harmonic of both the wheel and the tire is similar to rotating the tire counterclockwise by 350° (-10°) relative to the first random matching position of the wheel to obtain the worst match.
Conclusion
It is not satisfactory to only improve the manufacturing process of the tires or wheels to ensure that their respective spatial inhomogeneities are not satisfactory. Matching the highest point of the first harmonic of the wheel to the lowest point of the first harmonic of the tire is a “harmonious†solution that does not require additional cost and guarantees strength, safety and comfort.
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The meter can be connected with computer as follows. Connect the meter and computer with a USB-to-RS485 converter( converter A+ end to transmitter A+ end, B- to B-, and GND to GDN); turn to device manager of the computer to check COM port connected with meter. Start the software, select the right COM port and click Connect; do not change any other parameters (if you do not know the right one, click Automatic options on the left, click Connect, plug & unplug the transmitter, and then check if it is connected). You can click Connect on the tool bar to disconnect or connect again. It will shown Connected/Not Connected at the bottom of this interface.
The flow direction is settable. There are 4 options, forward(default), reverse, absolute value & bi-direction. There is a direction mark on the sensor. Forward means the same direction with the mark on sensor, the meter will only count the flow in this direction; reverse means the opposite direction of the mark, the meter will only count the reverse direction; bidirectional means that the meter will measure both directions, it increases when it is forward and decreases when reverse; absolute means it increases no matter it is forward or reverse.
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