SU412553A1 - DEVICE FOR MEASURING ROTATION SPEED - Google Patents

Description

The invention relates to the field of measurement and control of motion parameters.

The known devices for measuring the rotational speed, containing a frequency sensor and a measuring circuit made in the form of an electrically coupled amplifier, driver, and averaging unit, do not provide high accuracy.

The proposed device, for the purpose of improving accuracy, c) is sequentially switched between a driver and averaging unit by a matching circuit, a waiting multivibrator, a trigger and an amplitude limiter, as well as by a second coincidence circuit, its inputs connected to the waiting multivibrator and the trigger output, and its output It is connected to the input of the post and a quartz oscillator connected to both coincidence circuits.

FIG. 1 is a schematic diagram of the proposed device; in fig. 2 are timing diagrams of elements included in the device.

A device for measuring the rotational speed comprises: a frequency sensor /; amplifier 2; shaper 3; matching circuit 4; pending multivibrator 5; crystal oscillator 6; circuit 7 match; trigger 8; amplitude limiter 9, averaging unit 10.

The device works as follows.

Let the rotated shaft rotate with a certain angular velocity so that it is less than. FIG. 2, a). At the same time, at the output of the frequency sensor I, for example, a photoelectric, trapezoidal pulses appear (see Fig. 2.6), the follow-up period of which is T0. Having passed amplifier 2, these signals take the form of rectangular pulses (see Fig. 2, c) with a duration of ty. The shaper 3 to a pulse coming from the output of the amplifier 2 generates a rectangular pulse, the duration of which -Sf is practically chosen to be equal to two to three follow-up periods Tg of the impulse of the quartz oscillator 6. The output signal of the shaper 3 is shown in FIG. 2, g, and the output voltage of the crystal oscillator 6 is shown in FIG. 2, e. Signals from the output of the imaging unit 3 and the quartz oscillator 6 arrive at the inputs of the matching circuit 4, at the output of which pulses appear with the simultaneous existence of input effects. The output graph of coincidence circuit 4 is shown in FIG. 2, e.

At the time t of the occurrence of the first negative differential (marked in Fig. 2, e with an arrow) of the output signal of the coincidence circuit 4, the waiting multivibrator 5 is started, removing the voltage from the first input of the second coincidence circuit 7 for a time,

prohibit its operation. At the same time point, the waiting multivibrator 5 generates a triggering impulse arriving at the first input of the trigger 8. Time diagrams of the output signals of the waiting multivibrator 5 and trigger 8 are shown in FIG. 2, g and 2.3, respectively. When the starting pulse arrives from the standby multivibrator b, the trigger iS triggers and at its output instead of the zero signal a certain positive signal appears, which arrives at the second input of the matching circuit 7 and prepares its triggering on this input.

The part of the device, containing two 4 to 7 coincidence circuits, a crystal oscillator 6, G | Blowing multivibrator 5 and trigger 8, is designed to receive at its output to each pulse coming from the shaper 3 of a single straight pulse, the duration of which is equal to an integer and constant number periods following Gg pulses of a crystal oscillator 6, i.e.

t out J g

where n is an integer; n const.

In this case, l 3 and that part of the output signal of the crystal oscillator in, which determines the duration of Thy signal, the trilger 8, in FIG. 2, d is marked with shtrihovka. To accomplish this task, one should design the waiting multivibrator 5 so that

zhm - (p - - T ,.

Then after the time T «M (time tz in Fig. 2, g), the output of the waiting multivibrator 5 leads to a positive signal that will be fed to the first input of the matching circuit 7 and will remove the prohibition on its triggering. At the same time, a positive signal arriving from the output of the Quartz oscillator 6 appears at the third input of the matching circuit 7 (the time interval between the moments t and 4 of the time diagram shown in Fig. 2e). Thus, over all three inputs the matching circuit 7 prepared and at its output during the time interval (t, 4) there is a positive rectangular pulse (see Fig. 2, s).

At time f3, due to the end of the pulse coming from the quartz oscillator 6, a negative difference in the output signal of the matching circuit 7 is formed, marked in fig. 2, and an arrow. In this moment

the coincidence circuit 7, acts on the trigger 8 on the second input, causes it to trigger so that a zero level signal appears at its output. And since the leading and trailing edges of the output impulse of the trigger 8 were formed at the instants of the appearance of the same (negative) drops in the output signal of the quartz oscillator 6, the duration of the Toichi is always equal to

an integer number of periods following a quartz oscillator 6.

The output signal of the trigger 8 arrives at the input of the amplitude limiter 9, where the duration-stable pulses are additionally stabilized in amplitude at level A (see Fig. 2, k). From the output of the amplitude limiter 9, the signal is fed to the input of the averaging unit 10, which averages the sequence of square pulses with

constant volt-second area. The output graph of the averaging unit 10 is shown in FIG. 2, .d. In this way, the converter produces a DC voltage at the output.

  proportional to the input speed O) co.

When implementing a device of high stability requirements, the timing of the driver circuits of the standby multivibrator 5 is not presented. Indeed, if, under the influence of a changing ambient temperature, the duration tcm of the output pulse of the waiting multivibrator 5 changes within half the follow-up period G, the pulses of the quartz oscillator 6 (see Fig. 2, g), then this will not cause a change in your duration. output pulse trigger 8, since it is triggered at the time of occurrence of the same (negative) drops of the output signal of the crystal oscillator 6.

Subject invention

A device for measuring the rotational speed, comprising a frequency sensor and a measuring circuit made in the form of an electrically coupled amplifier, driver, and averaging unit, characterized by

By the fact that, in order to increase the accuracy, it is equipped with a matching circuit connected in series between the driver and the averaging unit, the waiting multivibrator, as well as the second matching circuit,

its inputs are connected to the waiting motor and to the trigger output, and its output is connected to the last of the latter and a quartz oscillator connected to both coincidence circuits.