US 5,205,320 AGranted

Flow rate control unit

AssigneeKYOCERA Corporation

InventorNoboru Nishimura

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Abstract

A flow rate control unit equipped with inner and outer dual cylinders in the housing of the unit, wherein the inner cylinder is normally urged by an elastic member to change the position of the upper section of the inner cylinder depending upon the balance between the above elastic force and the pressure of the fluid supplied in the housing so that the flow rate of the fluid to be discharged from the outlet of the housing can be controlled accordingly, characterized in that the outer and inner cylinders are made of ceramics to eliminate corrosion due to contact with fluid, and that the relationship between the average surface roughness of the inner circumferential surface of the outer cylinder and the average surface roughness of the outer circumferential surface of the inner cylinder is set within a range satisfying a formula to accurately discharge fluid at a constant flow rate.

Claims9

Dependent claims

A flow rate control unit comprising:

a fluid inlet;
a fluid outlet;
a ceramic outer cylinder defining a plurality of fluid passing holes coupled to the fluid outlet;
a ceramic inner cylinder defining a fluid inflow hole therein coupled to the fluid inlet;
and
an elastic member resiliently coupled to said inner cylinder;
said inner cylinder being movable inside said outer cylinder depending on the pressure difference between an interior and an exterior of said inner cylinder for changing the opening area of said fluid passing holes thereby maintaining the flow rate of a liquid discharged from said fluid inlet to said fluid outlet constant, said outer cylinder having an inner circumferential surface and said inner cylinder having an outer circumferential surface spaced a distance from said inner circumferential surface, wherein the relationship between an average surface roughness Ra.mu.m=X of the inner circumferential surface of said outer cylinder and an average surface roughness Ra.mu.m=Y of the outer circumferential surface of said inner cylinder satisfies the formula -4/7 X+0.4.ltoreq.Y.ltoreq.-3/7 X+1.35
where X.ltoreq.1.1 and Y.ltoreq.1.1.

5 more elements

Dependencies are inferred from the claim text.