SU379865A1 - USSR Dependent on auth. certificates K ° - Application November 17, 1971 (No. 1622082 / 26-25) with the accession of application No. - Priority - Published on July 20, 1973. Bulletin No. 20 Date of publication of the description 23.Vll.l973M. Cl. G 01p 27 / 22UDK 547.915 (088.8) - Google Patents

Description

one

The invention relates to the field of electro-automation of agricultural production processes and can be used, in particular, in measuring the milk fat content.

Milk is an electrolyte and, in addition to capacitive conductivity, has a high active conductivity. As a result, when measuring the fat content of milk by capacitive conductivity, significant errors occur, and sometimes it is practically impossible to measure.

In order to increase the accuracy of measurements and eliminate the effect of milk's active conductivity on the measurement results when determining the milk fat content of the proposed method, excitation shock excitation circuit is stimulated by square pulses and the fat content in milk is judged by the duration of the first pulse at the circuit output.

A capacitive milk fat content sensor is supplemented with a parallel inductance and the resulting circuit (g, L, C) is excited by square pulses. As a sensor of milk fat content, a coaxial cylinder made of stainless steel is used, the outer electrode diameter of which, the inner electrode 0.5 mm, and the height 30 mm.

FIG. 1 shows the equivalent circuit of the fat sensor used in the implementation of the proposed method; in fig. 2 is a circuit diagram of a device enabling the proposed method to be implemented; in fig. 3 shows the pulse diagrams at characteristic points of the circuit.

Equivalent fat sensor circuit contains capacitance C connected in parallel

and active resistance g (Fig. 1). The value of capacitance C is determined by the dielectric constant of the milk, which varies with the fat content of the milk. For example, when milk fat content changes in the range of 0.1 -12%, the dielectric constant of milk changes, respectively, in the range of 1500-600 units. Thus, a change in the fat content in milk leads to a change in the capacitance of the contour (g, L, C) of shock excitation. The use of the contour makes it possible to eliminate the effect of the active conductivity of milk on the process of measuring its fat content. The active conductivity of milk is not related to its fat content, but is determined mainly by the salt composition of milk and milk.

its temperature.

When a sequence of video pulses of a large porosity is applied to the input circuit, a transient occurs in the circuit, which is described by the equations U. R; gdt P., - by a barely simple transformation, we obtain the e. -ferential equation for drawing, and the contour. . n dU, 2/1, R g 7 2, G) - + 2 .- + uo (l + -j --- oV /, For the contour, equation (3) takes. dU. If, 2.0 1- ShoSU "o / L, at t 0; IL 0; i, I; C we obtain the solution of the differential equation 25 c-chi (4) e sin ((- cp), where w - I ojo - a is the frequency of free oscillations in circuit, φ is the initial phase shift. By changing the inductance L of the circuit, 35 it is possible to achieve such a mode in which in this case the velocity (0 ° and -: - (b) 40 Thus, "c does not depend on the active component g, but completely due to the value of C, since L const. When changing the fat content of milk, the capacitance C of the sensor changes and therefore frequency of the circuit on the circuit. The fixation changes the Cue, it is POSSIBLE to judge the change in the fat content of the milk. Consequently, the proposed method for determining laziness of milk fat is applicable and gives good results when there is an oscillatory mode in the shock excitation circuit, which includes a fat sensor mol an eye The oscillatory mode at con-65 5 10 15 (4) 20 (5) 30 55 round can be easily provided by selecting the appropriate value of the shunt inductance. The square pulses with a steep front (Fig. 3, a) from generator 1 are fed to the input of circuit 2, which uses the primary winding of transformer 3 as inductance (the transformer is used to separate the generator circuit from the rest of the circuit). The positive half-voltage of the diode 4 on the circuit (Fig. 3, d) is transferred to the key made up of transistors 5 and b and distinguishing the first positive half-wave. The key is in the open state until a negative half-wave appears in the voltage I (fig. 3, b), the diode 7 that trips the trigger on the transistors 8 and I opens the transistor 5, locks the transistor 6 thereby locking the key. The key is kept in the locked state for a time equal to the duration of the trigger in the operating mode, after which the trigger returns to the outcome and opens the key. This time is sufficient to complete the transition process in the circuit. The selected first half of the wave and the half-wave is fed to the input of the amplifier-limiter assembled on transistors 10 and 11; rectangular video pulses with a duration equal to half the period of the voltage on the circuit are formed at its output. With a change in the frequency of the voltage on the circuit, the duration of these pulses changes. The rest of the circuit converts the change in pulse duration into a proportional change in voltage. This part of the scheme works as follows. When a pulse arrives at the base of transistor 12 from the amplifier-limiting device, it closes and the capacitor 13 is charged through the speed 14 during the duration of the pulse (Fig. 3, e). The voltage across the capacitor 13, which is proportional to the pulse duration, is amplified by the transistor 15 and is measured by a pointer device 16, calibrated in% fat content. FIG. 3, e shows the case of measuring the voltage on the capacitor 13 for the two fat values Zhg and Zha. After the end of the pulse coming from the generator /, oscillations also occur in the circuit, but the first half-wave has a negative sign. She enters the trigger input, overturns it and thereby locks the key. The key, as in the first case, is in the locked state for the time necessary for the end of the transition process in the circuit. Thus, the trigger locks the key twice during one generator pulse (Fig. 3.6).

Subject invention

A method for determining milk fat content based on measuring the dielectric constant of a capacitive fat sensor included in a shock excitation circuit.

characterized in that, in order to improve the measurement accuracy, the shock excitation contour and the first impulse duration at the contour output are judged by rectangular pulses about the fat content in milk.

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