Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Reexamination Certificate
2000-11-28
2003-06-03
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
C073S054230, C073S054280, C073S054380, C073S054430
Reexamination Certificate
active
06571610
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to rotary rheometers which have a measurement motor rotating a measuring shaft on which an upper, and in particular a plate-shaped or conical, measuring part is fastened, wherein a measuring gap is formed between the measuring part and a rotationally fixed lower, preferably plate-shaped measuring part. The substance, such as fluid, gel or the like, to be tested is introduced into the said measuring gap and the with of the measuring gap can be adjusted by displacing two measuring parts relative to each other with a heating or temperature adjustment unit for the lower measuring part being arranged below this lower measuring part.
The fundamental design of rotary rheometers is known for example from Austrian Patent 404 192.
SUMMARY OF THE INVENTION
It is an object of the invention to be able, in the case of rotary rheometers of this type, in particular in the case of those of the type defined in the introduction, to set the temperature of the sample quickly and to keep it as precisely as possible to a desired value during measurement and to minimize temperature gradients in the sample. The viscosity of the samples—essentially fluids, gels, pastes, melts, up to solids—has a high degree of dependence upon temperature, which is in an order of magnitude of about a 10% change in viscosity per 1° C. For a precise determination of the viscosity, therefore, a homogeneous temperature of the sample inside the measuring gap is important. Since many samples also have their viscosity dependent upon time (for example thermo-setting adhesives), it has to be possible for temperature changes (heating and cooling) to be carried out in a precise manner in the shortest possible time.
These objects are attained in the case of a rotary rheometer of the type summarized above by providing at least one heat pump, and preferably at least one Peltier block, for supplying heat to or removing heat from the upper measuring part in order to heat, cool or adjust the temperature of the upper measuring part.
With the heat pump or pumps provided it is possible to supply heat to the upper measuring part or to remove heat from the upper measuring part very quickly, depending upon whether the temperature of the upper measuring part or of the sample to be tested or of the lower measuring part exceeds or does not reach a desired temperature value.
In a preferred embodiment of the invention a heat-conducting part is arranged about the measuring shaft of the rheometer to improve the supply of heat to or its removal from the upper measuring part in a rapid manner with the heat pump.
In a further preferred embodiment of the invention a gas or gas mixture of an appropriate temperature is supplied to the upper measuring part. In this way, in addition to the supply and removal of heat caused by thermal radiation and thermal conduction and the slight degree of convection always present, the temperature of the upper measuring part and/or the heat-conducting part can be altered or adjusted as desired by a suitably metered supply of the gas.
In addition, in a further preferred embodiment the upper and lower measuring parts, the Peltier block and any heat exchange that may be used are at least partially surrounded by a hood. The hood, in particular a thermally insulating hood, eliminates environmental action and insulates the measuring parts thermally from the surroundings.
Advantageous embodiments of the invention are set out in the following description, the claims, and the drawings.
REFERENCES:
patent: 2703006 (1955-03-01), Savins
patent: 3182494 (1965-05-01), Beatty et al.
patent: 3859906 (1975-01-01), Bratland
patent: 3935726 (1976-02-01), Heinz
patent: 4878379 (1989-11-01), Deer
patent: 5481903 (1996-01-01), King et al.
patent: 5710374 (1998-01-01), Ross et al.
patent: 6240770 (2001-06-01), Raffer
patent: 23 30 964 (1975-06-01), None
patent: 27 33 099 (1979-04-01), None
patent: 1 272 522 (1972-05-01), None
Ellenberger, J. et al., “Construction and Performance of a Cone-And-Plate Rheogoniometer with Air Bearings”, Journal Of Physics E, vol. 9, No. 9, Sep. 1976, pp. 763-765.*
Raha, S. et al., “Cone and Plate Rheometer for Polymer Melts”, Journal of Scientific Instruments (Journal of Physics E), Series 2, vol. 1, Nov. 1968, pp. 1113-1115.
Anton Paar GmbH
Townsend and Townsend / and Crew LLP
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