Fiber optic combustion pressure sensor with improved long-term reliability

Claim 2

In a fiber optic diaphragm sensor comprising a ferrule and having a cavity therein, a diaphragm attached to the ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, the diaphragm comprising a top, an underside, a periphery, and a skirt depending from the top and terminating at the periphery, the skirt being thicker nearer the top than at the periphery, an optical fiber inserted in the ferrule with the tip end of the optical fiber in communication with the cavity, the tip end being disposed to inject a light beam toward the diaphragm and to receive a light beam reflected from the diaphragm underside, the center of the diaphragm being thicker than an annular portion about the center.

Claim 3

The fiber optic diaphragm sensor according to claim 1 wherein the top forms a radius with the depending skirt.

Claim 4

The fiber optic diaphragm sensor according to claim 2 wherein the depending skirt thickness tapers decreasingly from near the underside to the periphery of the depending skirt.

Claim 5

In a fiber optic diaphragm sensor comprising a ferrule and having a cavity therein, a diaphragm attached to the ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, the ferrule having a first end near the diaphragm and a second end away from the diaphragm, an optical fiber inserted in the ferrule with the tip end of the optical fiber in communication with the cavity, the tip end being disposed to inject a light beam toward the diaphragm and to receive a light beam reflected from the diaphragm, and means for sealing the ferrule hermetically to the optical fiber nearer the second end of the ferrule away from the diaphragm, said ferrule of sufficient length to provide a substantial temperature differential along the length of the ferrule.

Claim 6

In a fiber optic diaphragm sensor comprising a ferrule and having a cavity therein, a diaphragm attached to the ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, the ferrule having a first end near the diaphragm and a second end away from the diaphragm, an optical fiber inserted in the ferrule with the tip end of the optical fiber in communication with the cavity, the tip end being disposed to inject a light beam toward the diaphragm and to receive a light beam reflected from the diaphragm, and means for sealing the ferrule hermetically to the optical fiber nearer the second end of the ferrule away from the diaphragm, said ferrule of sufficient length to provide a substantial temperature differential along the length of the ferrule.

Claim 7

The fiber optic diaphragm sensor according to claim 4 wherein the means for sealing comprises a low temperature activating means.

Claim 8

The fiber optic diaphragm sensor according to claim 4 wherein the means for sealing comprises soldering.

Claim 9

The fiber optic diaphragm sensor according to claim 4 wherein the means for sealing comprises brazing.

Claim 10

The fiber optic diaphragm sensor according to claim 4 wherein the means for sealing comprises polyimide-based epoxy.

Claim 11

The fiber optic diaphragm sensor according to claim 4 wherein the means for sealing comprises low temperature melting glass.

Claim 12

A process for positioning a ferrule having a distal and a proximal end relationship to a diaphragm in a fiber optic sensor comprising contacting the distal end of the ferrule to the diaphragm, deflecting the diaphragm to an extent reflecting a preselected particular value of pressure; and fastening the ferrule in place at the proximal end.

Claim 13

A process for positioning a ferrule having a distal and a proximal end relationship to a diaphragm in a fiber optic sensor comprising contacting the distal end of the ferrule to the diaphragm, deflecting the diaphragm to an extent reflecting a preselected particular value of pressure; and fastening the ferrule in place at the proximal end.

Claim 14

In a fiber optic diaphragm sensor comprising a ferrule and having a cavity therein, a diaphragm attached to the ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, an optical fiber inserted in the body, the optical fiber terminating adjacent the diaphragm, a stop formed on the ferrule, the stop being adjacent the diaphragm, and a part of the stop being angled whereby when the diaphragm under an excessive pressure contacts the ferrule, the angled part of the stop prevents damage to the optical fiber and ferrule.

Claim 15

In a fiber optic diaphragm sensor comprising a ferrule and having a cavity therein, a diaphragm attached to the ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, an optical fiber inserted in the body, the optical fiber terminating adjacent the diaphragm, a stop formed on the ferrule, the stop being adjacent the diaphragm, and a part of the stop being angled whereby when the diaphragm under an excessive pressure contacts the ferrule, the angled part of the stop prevents damage to the optical fiber and ferrule.

Claim 16

The fiber optic diaphragm sensor according to claim 11 wherein the stop comprises metal.

Claim 17

The fiber optic diaphragm sensor according to claim 11 wherein the stop is angled between 5 to 10 degrees.

Claim 18

In a fiber optic diaphragm sensor comprising an outer ferrule and having a cavity therein, a diaphragm attached to the outer ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted on the diaphragm, and an optical fiber inserted in an inner ferrule, the outer ferrule surrounding the inner ferrule, and the inner ferrule extending into the cavity to form a tip therein, the tip of the inner ferrule near the diaphragm being at least partly polished at an angle to form a stop for the diaphragm to prevent damage to the diaphragm, optical fiber and ferrule when the diaphragm is subjected to excessive pressure.

Claim 19

In a fiber optic diaphragm sensor comprising an outer ferrule and having a cavity therein, a diaphragm attached to the outer ferrule and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted on the diaphragm, and an optical fiber inserted in an inner ferrule, the outer ferrule surrounding the inner ferrule, and the inner ferrule extending into the cavity to form a tip therein, the tip of the inner ferrule near the diaphragm being at least partly polished at an angle to form a stop for the diaphragm to prevent damage to the diaphragm, optical fiber and ferrule when the diaphragm is subjected to excessive pressure.

Claim 20

The fiber optic diaphragm sensor according to claim 14 wherein the angle the tip of the inner ferrule is polished to is from 80 to 85 degrees.