Fuel additive agent supplying device for internal combustion engines

Claim 1

Apparatus by which air that has been passed through a filter can be supplied to a point of utilization at a substantially constant predetermined flow rate notwithstanding gradual plugging of the filter by dirt, and for indicating excessive plugging of the filter that renders it unuseable and necessitates its replacement, said apparatus comprising: A. a flowmeter comprising 1. an upright tube which is of progressively increasing inside diameter upwardly along its length, said tube being at least in part transparent so that its interior is visible along a substantial portion of its length, and 2. a lightweight body confined in said tube to be levitated by air flowing upwardly through the tube to a position along the length of the tube that depends upon the rate of such airflow; B. means defining an air intake in which a filter is replaceably installed; C. connection means communicated with the upper end of said upright tube and connectable with a point of air utilization; D. a manually adjustable throttling valve; and E. means defining an air flow path in series through the air intake, the lower end of said tube and said connection means, which flow path also incluDes the throttling valve arranged to control the rate of air flow therealong so that a uniform rate of air flow to the point of utilization can be maintained by adjusting the throttling valve by reference to the position of the body along the length of the tube, and so that the need for filter replacement is indicated by inability of the body to attain a predetermined such position with the throttling valve fully open.