RU36527U1 - Differential Rotational Viscometer - Google Patents

Description

Differential Tin Rotational Viscometer

The utility model relates to instruments for studying the rheological properties of liquid media and can be used in the automotive, food, construction, and petrochemical industries.

The proposed model is a type of rotational viscometers, which are two coaxial cylinders, while the viscosity of the fluid is a function of the moment of resistance to rotation.

Known rotational viscometer containing a rotating cylinder immersed in the measured substance, an asynchronous electric motor, on the shaft of which a cylinder is fixed, and a digital viscosity measuring system containing a pulse sensor of the period of rotation of the cylinder, mechanically connected to the motor shaft, the clock pulse generator. voltage-controlled electric motor source, pulse counter, constant time shaper, adder, the inputs of which are connected to the shaper and the sensor, and the output is connected to one counter input, the other input of which is connected to the output of the generator I. From the shaper there is a correction signal, of a certain value, set when the viscometer is operating in this 1-ion liquid, it is added or subtracted depending on the correspondingly hard or soft mechanical characteristics of the engine from the signal from the sensor, and the frequency of the resulting signal is independent of the engine torque.

This viscometer does not have a wide range of measurements with a significant complexity of the design scheme.

A rotational viscometer 2. is also known. It contains an electric drive, an external cylinder filled with the test fluid, in which an internal sensing cylinder, an angular displacement sensor, a recorder, a capacitor, an induction motor with excitation and control windings, on the axis of which on one side are placed coaxially with the external cylinder an external sensing cylinder is fixed and, on the other hand, an angular displacement sensor, an alternating voltage source, a common busbar and an amplifier connected by an input to the data output the angular displacement sensor and the output - to the bottom output of the control winding, one output of the excitation winding is connected through a capacitor to an AC voltage source: two A. amplitude detectors, a pulse generator, two digital-to-analog converters, a reversible counter and a co -parator. connected with one input to the output of the first amplitude detector, another input m - to the output of the first digital-to-analog converter

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G 01 N II

and an output - to one input of a reversible counter connected by another input to the output of the pulse generator and outputs - to the information inputs of both digital-to-analog converters, the first amplitude detector is connected by the input to the other output of the control winding, the second amplitude detector is connected by the input to the other output of the second excitation winding and the output - to the reference input of the second digital-to-analog converter, the output of which is connected to the input of the recorder.

This device also does not allow measurements of fluid viscosity in a wide range of shear rates, and at the same time has a rather complicated design.

The proposed utility model can significantly expand the measurement range with high accuracy and has a relatively simple design.

The proposed viscometer is a system of two coaxial cylinders, each of which is rotated by a direct current motor (gear motor), further comprises a system of permanent magnets to drive both cylinders and a system of screens and Hall sensors with built-in magnets; while the torque from the engine to the cylinder is transmitted through the interaction of magnetic fields of permanent magnets. A non-contact measuring system based on Hall sensors makes it possible to measure the rotational speed of each cylinder and the moment of rotation resistance, which is a function of the phase displacement of the driving and driven parts of the drive.

In FIG. 1 shows a structural diagram of a viscometer.

The differential type rotational viscometer contains an outer cylinder 1 filled with the test liquid 2, driven by a DC motor gearbox 3. By transmitting torque from the drive disk 4, fixed to the shaft of the motor gearbox 3 with nut 5, by means of the interaction of the magnetic fields of the constant system magnets 6, 7 and 8, to the driven cup 9, located coaxially with the shaft of the gear motor 3, which has a threaded connection with the cylinder 1. A similar design serves to rotate the inner cylinder 10. The whole structure is attached to the base 11.

The measuring system includes screens 12 (two for each cylinder) made of steel, and Hall sensors with built-in magnets 13 (also two for each cylinder), the outputs of which are connected via an analog-to-digital converter to computer 14.

The drive disk 4 is driven in rotation from the gear motor 3, the torque to the driven glass 9 is transmitted through the interaction of the magnetic fields of the permanent magnets 6, 7 and 8. Magnets 6 and 8 rotate the magnet 7 along with it, while in the absence of resistance, the disk 4 and the driven glass 9 with the outer cylinder 1 rotate synchronously, i.e. with the same angular velocity and initial phase. Similarly, and independently of the outer cylinder, the inner cylinder 10 is rotated.

In the presence of medium resistance 2, the central magnet 7 will shift relative to its original equilibrium position, while the drive disk 4 and the glass 9 will rotate at the same speed, but with some phase shift. This phase shift is proportional to the viscosity of the medium.

The rotation of the cylinders can occur in various, including opposite directions.

The measurement of the angular velocity of the cylinders, as well as the moment of resistance to rotation, is carried out by means of a contactless system. The screen, which is a thin steel disk, rotates at the same time as the glass 9 in the gap of the Hall sensor housing with an integrated magnet 13. The screen has projections and depressions. The sensor is supplied with voltage from the ADC of the computer 14. When the protrusion of the screen passes through the gap in the housing, the sensor generates a signal equal to the voltage supplied to it and transmitted to the computer with small losses; when passing the cavity - there is no signal. Thus, the Hall sensor works as a pulse counter, and therefore the cylinder speed.

A similar screen and sensor are installed on the master disk 4, which allows you to measure its rotation speed. In addition, such a system allows you to register and calculate the phase shift during rotation of the leading and driven parts of the viscometer with high accuracy.

A similar system is used to measure the angular velocity of the inner cylinder 10 and the moment of resistance to its rotation, which, obviously, is equal to the moment of resistance to rotation of the outer cylinder 1.

Thus, when two cylinders are rotated, signals from Hall sensors 13 are recorded, the rotational speeds of cylinders 1 and 10 are calculated (сОн and сОв, as well as phase shift df).

The resulting graph actually reflects the dependence of shear stresses on the shear rate of the medium.

The proposed design of the viscometer allows you to significantly expand the range of measurement of the viscosity of liquid media, as well as to study various liquids at various speed gradients in a centrifugal field while ensuring high accuracy and automation of measurements.

Sources used

1 USSR Author's Certificate No. 1249402, cl. G 01N 11/14. 1986.

2 Certificate of authorship No. 1627919, cl. G 01N 11/14/1991.

Claims (1)

A differential type rotational viscometer containing an inner cylinder placed in the test fluid filling the outer cylinder, coaxial with the inner one, characterized in that it further comprises a permanent magnet system associated with each cylinder, a system of screens and Hall sensors with built-in magnets, and both cylinders driven by a DC motor.