Abstract: An anemometer for measuring the velocity of a fluid. The anemometer has a pivotally mounted shaft with a drag element mounted thereon for exposure to the fluid. Electromagnets are orthogonally located adjacent to a ferrite block on the shaft, and changes in position of the shaft are sensed by changes in voltage across the electromagnets. A controller senses these voltage changes and applies current to the electromagnets to produce electromagnetic force to restore the position of the shaft and balance the fluid force on the drag element. A micro-processor computes fluid speed and direction from the current applied to the electromagnets.

Abstract: The anemometer is for use in measuring two orthogonal velocity components of a fluid, such as air or water. When used to measure wind speed, the wind force acting on a sphere attached to a shaft tends to deflect the shaft from the neutral position. This deflection is measured by optical or electromagnetic sensors which control an electromagnetic actuator which generates a force opposing the wind force thereby returning the shaft to the neutral position. The actuator generates a force proportional to the square of the current applied to the actuator coils. Since the drag force is proportional to the fluid velocity squared (for one dimensional measurement), the wind speed measurement derived from the current applied to the electromagnet will be partly linearized. A microprocessoris used to compute the wind speed components or the wind speed and its direction from the electromagnet signals.

Abstract: A swash plate assembly converts rotary motion to reciprocatory motion to reciprocate a diaphragm in a high frequency medical ventilator; the motor which drives the assembly is pivotally mounted for variation of the stroke of reciprocation thereby varying the tidal volume displaced by the diaphragm.