Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Patent
1992-06-02
1994-02-22
Williams, Hezron E.
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
73 5435, G01N 1114
Patent
active
052877329
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a rotary viscosimeter for measuring the viscosity of a liquid by bringing a rotor into contact with the liquid, and rotating the rotor via a spring, and in particular to a rotary viscosimeter which is capable of automatically measuring the viscosity characteristics by using a spring relaxation technique in an ultra-low fluid viscosity range.
BACKGROUND OF THE PRIOR ART
A rotary viscosimeter which measures the viscosity characteristics of a sample liquid in an ultra-low fluid viscosity range by using the relaxation of a spiral spring is disclosed in a report entitled "A new method for the viscosity measurement of paint in setting, sagging, levelling and penetration shear rate range of 0.001 to 1.0 reciprocal seconds using a cone/plate spring relaxation technique", by T. C. Patton, Journal of paint technology, Vol. 38, No. 502, November 1966. This viscosimeter is a multi-purpose rotary viscosimeter having a cone/plate rotor in a measuring unit (Wells-Brookfield micro viscometer RTV cone plate model).
The summary of the structure of such a viscosimeter is shown in FIG. 4. The viscosimeter includes a scale disc 3 secured to a drive shaft 2 which is rotated by a driving motor 1 with a reduction gear. A rotor shaft 5 is connected with the lower end 21 of the drive shaft 2 via a spring 4. A sample liquid 9, the viscosity of which is to be measured, is disposed between a cone rotor 6 and a plate 7 below the lower end of the rotor shaft 5. This condition is enlarged and shown in FIG. 5.
On the other hand, a pointing needle 8 which extends above the scale disc is secured to the rotor shaft 5 so that the relative angular displacement between the drive shaft 2 and the rotor shaft 5 can be read from the position of the pointing needle 8 on the scale disc 3. If the torsional spring constant of the spring 4, the size of the rotor 6 and the rotational speed of the rotor are determined, the scale pointed to by the needle 8 on the scale disc 3 is proportional to the viscosity of the sample liquid. Accordingly, the viscosity can be determined from the scale pointed to by the needle 8.
In the description of the operation principle of the viscosimeter set forth in the above mentioned report, it is assumed that the rotor shaft 5, the rotor 6 and the pointing needle 8 are engaged with the lower end 21 of the drive shaft. However, the system of the rotor shaft 5 is unstable in such a structure. Accordingly, in an actual viscosimeter, the rotor shaft 5a is borne by a pivot 11 and a bearing 12 made of gemstone as shown in FIG. 6 so that the upper end of the rotor shaft 5a is prevented from swinging by a pin 13 penetrating into a hole in the shaft. The other parts are represented with reference numerals suffixed with a of the corresponding parts in FIG. 4. However, 4a corresponding to the spring 4 in FIG. 4 denotes a spiral spring. 17 denotes a jacket for maintaining the sample liquid at a constant temperature, to which circulating water is introduced from a separately provided constant temperature bath.
Since both the pointing needle 8a and the scale disc 3a are rotating during measurement of the viscosity in the present viscosimeter, it is hard to read the scale pointed to by the needle during the rotation of these parts. Accordingly, standard operation of the present viscosimeter is performed as follows: After the indicated point or the scale has become stable after starting the rotation of the viscosimeter, a clamp lever 14 of FIG. 6 is depressed downward with a finger to push up a push-up chip 15 around a fulcrum 14'. This causes a scale disc shaft 16 engaged with the push-up chip 15 and the scale disc 3a linked with the shaft 16 to be lifted upward. As a result of this, the pointing needle 8a is clamped relative to the scale disc 3a to keep the scale position while the pointing needle 8a is engaged with one of a number of knurled grooves (not shown) formed on the outer periphery of the scale disc 3a and is rotated together therewith.
The pointing needle 8a is stopped
REFERENCES:
patent: 3886789 (1975-06-01), Brookfield
Roskos Joseph W.
Toki Sangyo Co., Ltd.
Williams Hezron E.
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