Device for preventing rotating speed measured value from jumping off and method thereof

Abstract

The invention relates to a device for preventing rotating speed measured value from fluctuating and a method thereof. The device comprises a centrifugal machine principal axis, a tachometer disc and a tachogenerator which are arranged on the principal axis and rotate with the principal axis synchronously; the tachogenerator is assembled by the following parts: n little magnets which are arranged on the tachometer disc and distributed evenly, and a Hall element sensor is firmly arranged near the little magnets; and the invention is characterized in that the Hall element sensor is connected with a PLC controller, the controller provides a high-speed counter (HSC) and a set time interrupter (STI) which have interruption function. Basically, the rising edge of measurement time t at every turn is aligned with that of the pulse to be tested, namely, timing begins from the rising edge of the pulse to be tested, so that the numbers of pulses measured in the measurement time t at every turn are basically equivalent, the velocity measurement is precise, and the fluctuating of the rotating speed measured value is avoided.

Description

technical field [0001] The invention relates to a speed measuring device and a speed measuring method thereof, in particular to a device and a method for preventing the measured value of a rotating speed from jumping. Background technique [0002] Speed ​​measurement is very important in manufacturing measurement. There are many methods of speed measurement, such as (1) permanent magnet DC tachogenerator speed measurement, which has high sensitivity and small linear error, but the brush structure is its inherent defect; (2) indirect Speed ​​measurement method, the speed signal is generated from the rotor position signal, eliminating the need for special electromagnetic or photoelectric speed measurement components, using integrated circuits to achieve indirect speed measurement, which is convenient and simple. The indirect speed measurement method is mainly used for small motors; the equipment used in the above test methods is simple and low cost. Inexpensive, but the speed ...

AI Technical Summary

Problems solved by technology

[0002] Speed ​​measurement is very important in manufacturing measurement. There are many methods of speed measurement, such as (1) permanent magnet DC tachogenerator speed measurement, which has high sensitivity and small linear error, but the brush structure is its inherent defect; (2) indirect Speed ​​measurement method, the speed signal is generated from the rotor position signal, eliminating the need for special electromagnetic or photoelectric speed measurement components, using integrated circuits to achieve indirect speed measurement, which is convenient and simple. The indirect speed measurement method is mainly used for small motors; the equipment used in the above test methods is simple and low cost. Inexpensive, but the speed measurement accuracy is too low

(3) Photoelectric speed measurement is a more general speed measurement method. The ordinary photoelectric method has low accuracy when measuring low speed, and the photoelectric code disc speed measurement accuracy is high, but the price is expensive; (4) Brushless DC speed measurement generator speed measurement, such as Hall-free The square wave brushless DC speed measurement integrated with the brush DC speed measurement and the motor, etc., has novel design, simple and compact structure, small size and good performance; the equipment used in this method is expensive

This invention uses a Hall sensor to measure the engine speed, which can basically guarantee the accuracy of the speed measurement. The Hall sensor is fixedly installed on the machine base to realize the non-contact speed measurement of the engine. However, in actual use, it is found that: even if the actual speed It is stable, but the measured rotational speed value is unstable, and the response is constantly changing in single digits. After analysis, the reason is that there is a lack of synchronization mechanism between the pulse sequence and the measurement time, and it is in a free state. It is this free state that causes The number of pulses measured each time is inconsistent

as attached figure 2 Shown: In the same measurement time t, due to the different starting points of the timing, within the same time t, 5 pulses are detected in the first pulse diagram, and 4 pulses are detected in the second pulse diagram , so the measured data is not accurate enough

Images