Low Pressure Transducer Using Beam and Diaphragm
A low-pressure transducer including a disc-shaped metal diaphragm to which a fluid pressure is applied, wherein the diaphragm contains a raised beam formed by thinning the entire exterior surface of the diaphragm except for the beam; and at least one silicon strain gage glass bonded to the beam, wherein the low-pressure transducer can accurately gage pressures at least as low as 15 psi. The present invention also comprises a method for manufacturing a pressure transducer including the steps of forming a cylindrical diaphragm having a top surface and a lower surface; establishing a diameter and a thickness of the diaphragm relative to an operational plane by a creating a hole axially through the transducer body that terminates at the lower surface; and creating a raised surface in the shape of a cross beam integral to the operational surface; and bonding one or more strain gages thereupon.
1 . A method for manufacturing a low pressure transducer including the steps of:
forming in a metal transducer body a cylindrical metal diaphragm having a top surface and a lower surface;
establishing a diameter and a thickness of the cylindrical metal diaphragm relative to an operational plane by creating a hole axially positioned through the transducer body that terminates at the lower surface of the diaphragm;
reducing the thickness of the metal diaphragm from its top surface to form thereon a raised surface in the shape of a beam integral to the top surface of the diaphragm; and
glass bonding one or more strain gages to the raised surface of the metal beam.
2 . The method of claim 1 , wherein the reducing comprising machining.
3 . The method of claim 2 , wherein the machining comprises electric discharge machining (EDM).
4 . The method of claim 1 , further comprising forming a central boss structure on the lower surface of the diaphragm opposite the beam.
5 . The method of claim 4 , wherein the forming the central boss structure comprises reducing the thickness of the metal diaphragm from its lower surface to form a boss thereon.
6 . The method of claim 1 , wherein the beam thickness is greater than the diaphragm thickness.
7 . The method of claim 1 , wherein the beam thickness is greater than twice the diaphragm thickness.
8 . The method of claim 5 , wherein the boss has a thickness between that of the beam thickness and the diaphragm thickness.
9 . The method of claim 1 , wherein said strain gages are silicon strain gages.
10 . A low-pressure fluid transducer comprising:
a metal body having a central bore defining a port for conveying a fluid pressure, the port terminating at an aft end of the body via a cylindrical metal diaphragm to which fluid pressure is applied, the metal diaphragm top surface having thereon a raised metal beam integral with the diaphragm and that crosses the diaphragm top surface;
at least one silicon strain gage glass bonded to a top surface of the raised metal beam, wherein the fluid pressure applied to the diaphragm lower surface deflects the diaphragm, producing a strain on the raised metal beam and the associated stain gage, thereby producing an electrical output indicative of the fluid pressure.
11 . The transducer of claim 10 , wherein the metal beam thickness is greater than the diaphragm thickness.
12 . The transducer of claim 10 , wherein the beam thickness is greater than twice the diaphragm thickness.
13 . The transducer of claim 10 , wherein the strain gages are silicon strain gages.
14 . The transducer of claim 10 , further comprising a central boss monolithically formed on the lower surface of the diaphragm opposite the beam.
15 . The transducer of claim 14 , wherein the boss has a thickness between the beam thickness and the diaphragm thickness.
16 . The transducer of claim 10 , wherein the metal diaphragm is stainless steel.
17 . The transducer of claim 16 , wherein the metal diaphragm has a thickness of 0.0035 inch, and wherein the metal beam has a thickness of 0.075 inch.
18 . The transducer of claim 16 , wherein a central boss monolithically formed on the lower surface of the diaphragm opposite the beam has a thickness of 0.063 inch.