Honeywell G.m.b.h.

George E Hershey

Douglas W Wilda

Charles E Lane, Iii

A pressure transmitter assembly includes a laminated ceramic structure for providing fluid passages as well as a support for a pressure sensor, electronic circuitry, fluid barrier diaphragms and input process fluid connections. The laminated structure is comprised of a plurality of co-fired ceramic layers having the fluid passages molded therein to enable fill fluids within the assembly to apply input pressures as a differential pressure across the pressure sensor. In one embodiment of the invention, three ceramic layers are used while a second embodiment uses four layers with an overload diaphragm captured between two of the layers. The laminated ceramic structure can be extended in either embodiment to include an outer ceramic circuit board which is bonded with a fluid-tight interface with an adjacent one of the other ceramic layers. Electronic components are mounted on the circuit board, either before or after bonding, which also provides a capability for further fluid passages extending between the circuit board and an adjacent ceramic layer.

Pressure transmitter assembly

An adjustable overload mechanism for a differential fluid pressure transmitter includes a first and a second overload control diaphragm and an adjustable spring pressure means for applying an adjustable preload pressure to the control diaphragms. The spring pressure means for each diaphragm includes a spring such as a Belleville washer spring located between a diaphragm back-up plate in contact with a side of the control diaphragm and a wedge shaped support for the Belleville washer spring. A wedge shaped drive means is arranged to be selectively movable with respect to the wedge shaped spring support while maintaining the sloping wedge surfaces in contact. An adjustable drive screw is connected to the drive wedge to provide a means for changing the relative position of the support wedge and drive wedge. The relative motion between the two wedge shaped elements displaces the support wedge transversely to the Belleville washer to change the height of the Belleville washer which affects the preload or spring pressure against the control diaphragm. Each control diaphragm is used to control the valving of a fill fluid in contact with a respective barrier diaphragm subjected to an input fluid pressure. The fill fluid is pressurized by the movement of the barrier diaphragm and transmits the input pressure to a pressure sensor. An excessive or overload input pressure overcomes the preload or spring pressure biasing the control diaphragm to divert the fill fluid displaced by the barrier diaphragm to protect the sensor from the overload pressure.

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Ardsley, PA, United States of America

George E Hershey