Viscosimeter

Claim 1

A viscosimeter comprising: a probe having an input lead and an output lead; a loop circuit having an input lead connected from said probe output lead, a first output lead connected to said probe input lead, and a second output lead, said probe and said loop circuit forming an electromechanical oscillator, said probe including a vibratable structure immersable in a fluid, means connected from said probe input lead to vibrate said vibratable structure, a transducer, means connecting said transducer to said first and second output leads, said last named connection producing first and second varying signals on said first and second output leads, respectively both of the same frequency as that at which said vibratable structure vibrates, said first signal having periods T a and T b at different times, the product of the kinematic viscosity and density of said fluid being a function of said periods T a and T b ; utilization means; output means connecting said loop circuit second output lead to said utilization means; and phase adjustment means connected to said loop circuit for periodically switching the phase of one of said first and second signals so that said one signal phase altnerates between two different values relative to the phase of the other signal, said one signal being connected from one of said first and second output leads wherein means are connected from said one output lead to provide a signal proportional to the viscosity v of said fluid thus: ##EQU2## where T a is the period during which said one signal lags, T b is the period during which said one signal leads, and A, B, C, A', B' and C' are constants such that A'+B'T a +C'T a 2 is directly proportional to the density of said fluid.