Abstract: A monolithic capacitive differential pressure transducer (68, 156, 170) is shown composed of ceramic material having first and second cavities formed adjacent to opposed face surfaces to form first and second flexible diaphragms (70, 72; 110, 140; 172, 174) and a motion transfer pin (74, 124/130, 202) attached to and extending between the diaphragms. Capacitor plates are disposed on opposed rigid platform members (76, 78; 100, 126; 184, 194). Component parts are first pressed from ceramic powder and assembled into a unit using one of several methods including a selected amount of pressure to press them together or using a combination of low pressure along with raising the temperature of the material to soften the binder in the ceramic material at surfaces of the parts which are to be joined together.

Abstract: A pressure system has a pressure vessel holding gas under pressure and has a pressure responsive device arranged to be responsive to loss of gas from the vessel to provide a warning signal or the like corresponding to the gas loss. The device has two springs opposing movement of a device diaphragm in response to the gas pressure in the vessel, one spring being arranged to oppose diaphragm movement resulting from change in the gas pressure due to change in gas temperature from a selected temperature in accordance with the gas law, and the other spring being arranged to permit diaphragm movement to change position of a control to provide a signal corresponding to a gas loss when change in the gas pressure in the vessel decreases to a selected level at the selected gas temperature.

Abstract: A pressure sensor comprises an improved capacitive pressure transducer having a first capacitor plate secured to a limited portion of a first surface of a relatively rigid ceramic substrate and having a diaphragm with an electrically conductive surface forming a second capacitor plate, the diaphragm being secured to the ceramic substrate at a location spaced inwardly from the periphery of that first substrate for disposing the second capacitor plate in spaced, overlying relation to the first capacitor plate to be movable in response to applied pressure for varying the capacitor formed by the plates. Support means bear against opposite surfaces of the ceramic substrate at the periphery of the substrate for mounting the transducer with the diaphragm thereof substantially free of mounting stresses to be exposed to a pressure force in a pressure zone to be monitored.

Abstract: A pressure sensor comprises an improved capacitive pressure transducer having a first capacitor plate secured to a limited portion of a first surface of a relatively rigid ceramic substrate and having a diaphragm with an electrically conductive surface forming a second capacitor plate, the diaphragm being secured to the ceramic substrate at a location spaced inwardly from the periphery of that first substrate surface for disposing the second capacitor plate in spaced, overlying relation to the first capacitor plate to be movable in response to applied pressure for varying the capacitor formed by the plates. Support means bear against opposite surfaces of the ceramic substrate at the periphery of the substrate for mounting the transducer with the diaphragm thereof substantially free of mounting stresses to be exposed to a pressure force in a pressure zone to be monitored.

Abstract: A dual function sensor particularly useful with vehicular coolant systems indicates when a coolant liquid becomes corrosive to such cooling system materials as well as when the liquid falls to a low level condition. A reference and a sense electrode are used to probe the condition of the coolant liquid. Integral electronics provide signal conditioning and transmitting to indicate both corrosive and low level coolant conditions. The sensor assembly mounts directly onto a tubular coupling on the vehicle radiator by pushing the assembly onto the coupling until a spring wire element snaps past a lip formed on the free distal end of the coupling. An electrical connector shroud extends from the assembly and accommodates a mating male connector which is pushed onto the shroud until a clip mounted on the male connector snaps over a locking tab located on the shroud. The male connector typically is connected to an engine control module (ECM).

Abstract: A relatively low cost, high performance pressure responsive switch device comprises a base, switch means mounted on the base, and a discrete pressure-responsive unit which is separately testable for predetermining its pressure response characteristics and which is then mounted on the base for moving the switch means between selected switch positions in response to the application of a selected fluid pressure. The discrete pressure-responsive unit is particularly adapted for achieving long unit cycle life under high operating pressure conditions and for actuating the switch means incorporated in the device to achieve long cycle life as well.

Abstract: A thermal or pressure responsive switch has a contact arm movable between switch positions opening and closing switch contacts, has a spring biasing the arm to one of the switch positions, and has a dished disc element movable with snap action between original and dished configurations during changes in pressure or temperature conditions. The dished disc element cooperates with the spring in moving the contact arm between switch positions on the occurrence of selected switch actuating or reset pressure or temperature conditions, and the switch components are arranged to permit overtravel of the disc during snap acting movement for closing switch contacts without substantially altering the pressure or temperature response characteristics of the switch.