초록 ▼

Disclosed is a particle sensor having a light beam with a beam long axis and an air flow tube with an inlet end and a particle exit mouth. In an aspect of the invention, the cross-sectional area of the flow passage at the inlet end is greater than the cross-sectional area of the exit mouth. This enl

Disclosed is a particle sensor having a light beam with a beam long axis and an air flow tube with an inlet end and a particle exit mouth. In an aspect of the invention, the cross-sectional area of the flow passage at the inlet end is greater than the cross-sectional area of the exit mouth. This enlarged area dramatically reduces pressure drop along the tube. The exit mouth is in registry with the light beam and is elongate in a direction substantially parallel to the beam long axis. Thus, particles flowing through the mouth pass through the beam. In another aspect, the invention includes a centrifugal blower which is light in weight and which may be battery powered.

대표청구항 ▼

A particle sensor using scattered light for analyzing airborne particles entrained in air drawn from an environment into the particle sensor, such sensor including: a variable-speed centrifugal blower having a housing, a motor and an exhaust port; an opening in the blower housing; a particle detecti

A particle sensor using scattered light for analyzing airborne particles entrained in air drawn from an environment into the particle sensor, such sensor including: a variable-speed centrifugal blower having a housing, a motor and an exhaust port; an opening in the blower housing; a particle detection system including a sensing portion having a light-scatter sensing cavity; an air flow tube and a low-pressure-drop nozzle in air flow communication with the sensing cavity and with the opening in the blower housing; a circuit connected to the motor for providing a speed-controlling variable voltage to the motor; a flow sensor for providing a speed-affecting signal to the circuit; an exhaust filter interposed between the exhaust port and the environment; and wherein: the particle detection system further includes (a) a light source, (b) a device directing light scattered by a particle entering the cavity through the air flow tube and the nozzle, and (c) a detector for receiving light directed by the device; and the air flowing in the sensing cavity through the air flow tube is drawn through such sensing cavity by the centrifugal blower, flows at a flow rate dependent upon the speed of the blower motor and is discharged from the particle sensor through the exhaust filter.