Pressure transmitter with simplified pressure sensing head
First Claim
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1. A pressure sensing head comprisinghead structure having a substantially flat back-up surface,a substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said surface so that said first face faces said surface,means for applying a fluid pressure force to said second face which is representative of a fluid pressure to be sensed, said surface physically matching said first face sufficiently to fully back up and support said diaphragm and prevent its deleterious deformation in the presence of values of said fluid pressure force which force said diaphragm to bottom-out against said surface,a first fluid chamber of expansible volume having fluid communication with said first face, anda preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and exerting a deforming force on said first face which deforms and bows-out said diaphragm away from said surface into a dome shape to form a second fluid chamber between said first face and said surface which is completely filled with said fluid,said diaphragm stiffness and said fill fluid quantity, and hence said deforming force, being preselected, in the absence of said fluid pressure force on said second face, to cause said deforming force normally to bow-out said diaphragm by a preselected amount to a normal bowed-out position for which the traversal of said fluid pressure force throughout its normal operating range deflects said diaphram about its said normal bowed-out position to only that extent which causes said diaphragm to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic,whereby the pressure of said fill fluid is consistently representative of said fluid pressure to be sensed throughout said normal operating range.
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Abstract
A differential pressure to electrical signal transmitter has a pair of flat barrier diaphragms and a central control diaphragm located between the barrier diaphragms. First chambers between one of the barrier diaphragms and the control diaphragm, and a first length of capillary tubing connected between the first chambers and one chamber of a remotely located sensor capsule, are filled with a first incompressible fill liquid. Second chambers between the other barrier diaphragm and the control diaphragm, and a second length of capillary tubing connected between the second chambers and another chamber of the sensor capsule, are filled with a second incompressible fill liquid. The fill liquids are made to pump up their respective flat barrier diaphragms to cause the latter to have a dome shape and hence to be free from "oil canning." A chamber on the outside of one barrier diaphragm is pressurized with a first fluid, and a chamber on the outside of the other barrier diaphragm is pressurized with a second fluid. The pressures of the two fill liquids act on the opposite sides of a minute displacement sensing element, located between the two sensor chambers, to displace the element and cause it to produce an electrical output signal which is dependent upon the difference between the fill liquid pressures, and hence upon the difference between the pressures of the first and second fluids.
42 Citations
15 Claims
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1. A pressure sensing head comprising
head structure having a substantially flat back-up surface, a substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said surface so that said first face faces said surface, means for applying a fluid pressure force to said second face which is representative of a fluid pressure to be sensed, said surface physically matching said first face sufficiently to fully back up and support said diaphragm and prevent its deleterious deformation in the presence of values of said fluid pressure force which force said diaphragm to bottom-out against said surface, a first fluid chamber of expansible volume having fluid communication with said first face, and a preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and exerting a deforming force on said first face which deforms and bows-out said diaphragm away from said surface into a dome shape to form a second fluid chamber between said first face and said surface which is completely filled with said fluid, said diaphragm stiffness and said fill fluid quantity, and hence said deforming force, being preselected, in the absence of said fluid pressure force on said second face, to cause said deforming force normally to bow-out said diaphragm by a preselected amount to a normal bowed-out position for which the traversal of said fluid pressure force throughout its normal operating range deflects said diaphram about its said normal bowed-out position to only that extent which causes said diaphragm to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic, whereby the pressure of said fill fluid is consistently representative of said fluid pressure to be sensed throughout said normal operating range.
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4. A pressure sensing head comprising
head structure having a substantially flat back-up surface and a second surface, a substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said back-up surface so that said first face faces said back-up surface, means for applying a fluid pressure force to said second face which is representative of a fluid pressure to be sensed, said back-up surface physically matching said first face sufficiently to fully back up and support said diaphragm and prevent its deleterious deformation in the presence of values of said fluid pressure force which force said diaphragm to bottom-out against said back-up surface, a control diaphragm mounted in spaced and peripherally sealed relationship to said second surface to form a first fluid chamber of expansible volume between one side of said control diaphragm and said second surface, passage means providing fluid communication between said first chamber and said first face, and a preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and said passage means and exerting a deforming force on said first face which deforms and bows-out said barrier diaphragm away from said back-up surface into a dome shape to form a second fluid chamber between said first face and said back-up surface which is completely filled with said fluid, said barrier diaphragm stiffness and said fill fluid quantity, and hence said deforming force, being preselected, in the absence of said fluid pressure force on said second face, to cause said deforming force normally to bow-out said barrier diaphragm by a preselected amount to a normal bowed-out position for which the traversal of said fluid pressure force throughout its normal operating range deflects said barrier diaphragm about its said normal bowed-out position to only that extent which causes said barrier diaphragm to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic, whereby the pressure of said fill fluid is consistently representative of said fluid pressure to be sensed throughout said normal operating range.
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5. A pressure sensing head comprising
head structure having first and second substantially flat back-up surfaces, a third surface, and a fourth surface, a first substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said first back-up surface so that said first face faces said first back-up surface, a second substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said second back-up surface so that said first face of said second barrier diaphragm faces said second back-up surface, means for applying a first fluid pressure force to said second face of said first barrier diaphragm which is representative of a first fluid pressure to be sensed, said first back-up surface physically matching said first face of said first barrier diaphragm sufficiently to fully back up and support said first barrier diaphragm and prevent its deleterious deformation in the presence of values of said first fluid pressure force which force said first barrier diaphragm to bottom-out against said first back-up surface, means for applying a second fluid pressure force to said second face of said second barrier diaphragm which is representative of a second fluid pressure to be sensed, said second back-up surface physically matching said first face of said second barrier diaphragm sufficiently to fully back up and support said second barrier diaphragm and prevent its deleterious deformation in the presence of values of said second fluid pressure force which force said second barrier diaphragm to bottom-out against said second back-up surface, a control diaphragm mounted in spaced and peripherally sealed relationship to said third and fourth surfaces to form a first fluid chamber of expansible volume between one side of said control diaphragm and said third surface, and to form a second fluid chamber of expansible volume between the other side of said control diaphragm and said fourth surface, first passage means providing fluid communication between said first chamber and said first face of said first barrier diaphragm, second passage means providing fluid communication between said second chamber and said first face of said second barrier diaphragm, a first preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and said first passage means and exerting a deforming force on said first face of said first barrier diaphragm which deforms and bows-out said first barrier diaphragm away from said first back-up surface into a dome shape to form a third fluid chamber between said first face of said first barrier diaphragm and said first back-up surface which is completely filled with said fluid, and a second preselected quantity of a substantially incompressible fill fluid completely filling said second chamber and said second passage means and exerting a deforming force on said first face of said second barrier diaphragm which deforms and bows-out said second barrier diaphragm away from said second back-up surface into a dome shape to form a fourth fluid chamber between said first face of said second barrier diaphragm and said second back-up surface which is completely filled with said fluid, said stiffnesses of said barrier diaphragms and said quantities of said fill fluids, and hence said deforming forces, being preselected, in the absence of said fluid pressure forces on said second faces, to cause said deforming forces normally to bow-out the respective barrier diaphragms by preselected amounts to normal bowed-out positions for which the traversal of the difference between said first and second fluid pressure forces throughout its normal operating range deflects said barrier diaphragms about their normal bowed-out positions to only those extents which cause said barrier diaphragms to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform unvarying, and consistent deflection vs. pressure characteristic, whereby the difference between the pressures of said first and second fill fluids is consistently representative of the difference between said first and second fluid pressures to be sensed throughout said normal operating range.
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6. A differential pressure to electrical signal transmitter comprising
head structure having a substantially flat back-up surface, a substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said surface so that said first face faces said surface, means for applying a fluid pressure force to said second face which is representative of a first fluid pressure to be sensed, said surface physically matching said first face sufficiently to fully back up and support said diaphragm and prevent its deleterious deformation in the presence of values of said fluid pressure force which force said diaphragm to bottom-out against said surface, a first fluid chamber of expansible volume having fluid communication with said first face, a preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and exerting a deforming force on said first face which deforms and bows-out said diaphragm away from said surface into a dome shape to form a second fluid chamber between said first face and said surface which is completely filled with said fluid, said diaphragm stiffness and said fill fluid quantity, and hence said deforming force, being preselected, in the absence of said fluid pressure force on said second face, to cause said deforming force normally to bow-out said diaphragm by a preselected amount to a normal bowed-out position for which the traversal of said fluid pressure force throughout its normal operating range deflects said diaphragm about its said normal bowed-out position to only that extent which causes said diaphragm to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic, differential pressure sensor means including a sensing element having first and second element portions and an electrical output connection and operative to produce in said output connection a signal representative of the difference between the pressures of two fluids acting, respectively, on said first and second element portions, first means for applying the pressure of said fill fluid to said first element portion, and second means for applying to said second element portion a second fluid pressure to be sensed, whereby the difference between the pressures acting on said first and second element portions is consistently representative of the difference between said first and second fluid pressures to be sensed throughout said normal operating range.
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10. A differential pressure to electrical signal transmitter comprising
head structure having a substantially flat back-up surface and a second surface, a substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said back-up surface so that said first face faces said back-up surface, means for applying a fluid pressure force to said second face which is representative of a first fluid pressure to be sensed, said back-up surface physically matching said first face sufficiently to fully back up and support said diaphragm and prevent its deleterious deformation in the presence of values of said fluid pressure force which force said diaphragm to bottom-out against said back-up surface, a control diaphragm mounted in spaced and peripherally sealed relationship to said second surface to form a first fluid chamber of expansible volume between one side of said control diaphragm and said second surface, differential pressure sensor means including a sensing element having first and second element portions and an electrical output connection and operative to produce in said output connection a signal representatiive of the difference between the pressures of two fluids acting, respectively, on said first and second element portions, passage means providing fluid communication between said first chamber, said first face, and said first element portion, a preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and said passage means and exerting a deforming force on said first face which deforms and bows-out said barrier diaphragm away from said back-up surface into a dome shape to form a second fluid chamber between said first face and said back-up surface which is completely filled with said fluid, said barrier diaphragm stiffness and said fill fluid quantity, and hence said deforming force, being preselected, in the absence of said fluid pressure force on said second face, to cause said deforming force normally to bow-out said barrier diaphragm by a preselected amount to a normal bowed-out position for which the traversal of said fluid pressure force throughout its normal operating range deflects said barrier diaphragm about its said normal bowed-out position to only that extent which causes said barrier diaphragm to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic, and means for applying to said second element portion a second fluid pressure to be sensed, whereby the difference between the pressures acting on said first and second element portions is consistently representative of the difference between said first and second fluid pressures to be sensed throughout said normal operating range.
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13. A differential pressure to electrical signal transmitter comprising
head structure having first and second substantialy flat back-up surfaces, a third surface, and a fourth surface, a first substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said first back-up surface so that said first face faces said first back-up surface, a second substantially flat, deformable barrier diaphragm of a preselected stiffness having first and second faces and a peripheral edge which is sealed to said second back-up surface so that said first face of said second barrier diaphragm faces said second back-up surface, means for applying a first fluid pressure force to said second face of said first barrier diaphragm which is representative of a first fluid pressure to be sensed, said first back-up surface physically matching said first face of said first barrier diaphragm sufficiently to fully back up and support said first barrier diaphragm and prevent its deleterious deformation in the presence of values of said first fluid pressure force which force said first barrier diaphragm to bottom-out against said first back-up surface, means for applying a second fluid pressure force to said second face of said second barrier diaphragm which is representative of a second fluid pressure to be sensed, said second back-up surface physically matching said first face of said second barrier diaphragm sufficiently to fully back up and support said second barrier diaphragm and prevent its deleterious deformation in the presence of values of said second fluid pressure force which force said second barrier diaphragm to bottom-out against said second back-up surface, a control diaphragm mounted in spaced and peripherally sealed relationship to said third and fourth surfaces to form a first fluid chamber of expansible volume between one side of said control diaphragm and said third surface, and to form a second fluid chamber of expansible volume between the other side of said control diaphragm and said fourth surface, differential pressure sensor means including first and second sensor chambers, an electrical output connection, and a sensing element which is subjected to and responsive to the pressure difference between fluids within said first and second sensor chambers to produce in said output connection a signal representative of said pressure difference, first passage means providing fluid communication between said first fluid chamber, said first face of said first barrier diaphragm, and said first sensor chamber, second passage means providing fluid communication between said second fluid chamber, said first face of said second barrier diaphragm, and said second sensor chamber, a first preselected quantity of a substantially incompressible fill fluid completely filling said first chamber and said first passage means and exerting a deforming force on said first face of said first barrier diaphragm which deforms and bows-out said first barrier diaphragm away from said first back-up surface into a dome shape to form a third fluid chamber between said first face of said first barrier diaphragm and said first back-up surface which is completely filled with said fluid, and a second preselected quantity of a substantially incompressible fill fluid completely filling said second chamber and said second passage means and exerting a deforming force on said first face of said second barrier diaphragm which deforms and bows-out said second barrier diaphragm away from said second back-up surface into a dome shape to form a fourth fluid chamber between said first face of said second barrier diaphragm and said second back-up surface which is completely filled with said fluid, said stiffnessess of said barrier diaphragms and said quantities of said fill fluids, and hence said deforming forces, being preselected, in the absence of said fluid pressure forces on said second faces, to cause said deforming forces normally to bow-out the respective barrier diaphragms by preselected amounts to normal bowed-out positions for which the traversal of the difference between said first and second fluid pressure forces throughout its normal operating range deflects said barrier diaphragms about their normal bowed-out positions to only those extents which cause said barrier diaphragms to deflect without oil canning, and thus to deflect with only an essentially continuous, uniform, unvarying, and consistent deflection vs. pressure characteristic, whereby the difference between the pressures of said fluids within said first and second sensor chambers is consistently representative of the difference between said first and second fluid pressures to be sensed throughout said normal operating range.
Specification
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Current AssigneeHoneywell Incorporated (Honeywell International Inc.)
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Original AssigneeHoneywell Incorporated (Honeywell International Inc.)
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InventorsMedlar, Lewis A., Newbold, William F.
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Primary Examiner(s)Yasich, Daniel M.
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Application NumberUS05/837,714Time in Patent Office677 DaysField of Search73/716, 73/717, 73/718, 73/719, 73/720, 73/721, 73/722, 73/706US Class Current73/708CPC Class CodesG01L 13/025 using diaphragmsG01L 19/0038 being part of the housing o...G01L 19/148 Details about the circuit b...G01L 9/0054 integral with a semiconduct...
