Texas Instruments Corporation

Werner Strasser

Youn H Ting

Mitchell R Rowlette

John T Hancock

John A Haug

Edward C Lewis

Stanley F Kummer

Bryan C Jansen

Tim H McMains

Richard T Gordon

An electric switch is shown which is responsive separately to two different conditions, i.e. temperature and pressure. The switch includes a temperature sensing disc and a pressure sensing disc both coupled through several alternate motion transfer arrangements to the movable electrical contact of the switch. Several structures are shown for mounting a switch on a surface so that the pressure sensing disc is exposed to fluid pressure and the temperature sensing disc is thermally coupled to the surface.

Dual condition responsive switch apparatus

A pressure sensing element having a housing including a flexible membrane receiving portion, a flexible disc member of predetermined shape secured within the housing, and a flexible membrane disposed within the housing, the flexible membrane being substantially more flexible than the disc member, the membrane having an outer portion hermetically secured to the membrane receiving portion, a central portion impinging against the disc member and conforming to the shape thereof and an intermediate unsupported portion joining the interior portion of the outer portion and the exterior portion of the central portion. The hermetically sealed diaphragm is obtained by providing a diaphragm capable of deforming to a fixed shape, hermetically securing the edge portion of the diaphragm to a securing member, and then forcing a central portion of the diaphragm under sufficient pressure against a surface of predetermined shape and more rigid than the diaphragm to cause the central portion of the diaphragm to conform to the shape of the surface and provide an unwrinkled planar central diaphragm.

Hermetic pressure sensor

Differentially connected capacitive sensors are mechanically coupled with the flexible capacitor plate of one sensor coupled to the source of pressure to be measured, the flexible capacitor plate of the other sensor coupled to ambient pressure. In a second embodiment, inaccuracies due to forces on the flexible plate are minimized by providing a housing with a tapered inner wall, an O-ring and a support to apply a radial load to the sensor due to clamping action from the tapered housing against the O-ring to provide a seal for the pressure sensing chamber. In a further embodiment, the cost of fabrication of the pressure transducer is minimized by providing the housing as a one piece cup. The electronics are mounted on the exterior surface of the low pressure side of the ceramic capacitor pressure sensing element and sealed in thereat by potting with an epoxy. In addition, an electrical pin connector from the electronics and a vent to the low pressure surface of the movable plate are secured in the potting material and extend externally thereof. In a further embodiment, pressures applied to the movable diaphragm of the pressure sensing element by the gasket are eliminated by providing a ceramic capacitor having a movable diaphragm element having smaller length and width dimensions than the fixed capacitor substrate. The gasket is positioned around the movable diaphragm element and on the fixed capacitor plate with the housing being stepped to apply a force against the gasket but remain out of contact with the movable diaphragm element.

Low pressure sensor

A pressure sensor probe has a first port connectable to a relatively low pressure source in a compressor crankcase and a second port connectable to a relatively high pressure source at the output of an oil pump. A shuttle is slidably disposed in a bore and has a first end which closes the first port when the difference in pressure between the two ports indicative of normal operation exceeds a selected value determined by the relative areas of the shuttle exposed to the respective pressures and by a coil spring which biases the shuttle away from the first port. A passage is formed between the shuttle and the bore leading from the second port to a force receiving surface on the high pressure side of the shuttle. The length and cross sectional area of the passage is selected to provide a desired dampening or time delay between the high pressure source and the force receiving surface. Indicator means responsive to the position of the shuttle is used to indicate the status of the oil differential between the two ports and, if desired, to control the actuation of the compressor motor.

Lubrication sensor apparatus

A hermetically sealed, creep acting pressure switch has a sensor assembly comprising a bulged metallic membrane welded between a port fitting and a support. A switch assembly, attached to the sensor assembly, includes a housing which has a switch chamber in which, in one embodiment, a pair of stationary contacts are mounted. A piston having a force receiving surface at one end is biased into engagement with the membrane with an adjustable calibrated force. An electrically conductive contact bridge is mounted on and is movable with the piston. The switch can be normally open or normally closed depending on which side of the contact bridge the stationary contacts are mounted. In an alternate embodiment a miniature switch is mounted in the switch chamber and is adapted to be actuated by the piston.

Method for making a pressure responsive switch

Pressure responsive switch having little or no differential between

A sealed pressure-responsive switch is manually resettable and trip-free. The switch has a separate snap-acting, bistable, dished metal disc or disc element disposed between a sealed snap-acting pressure-responsive diaphragm and a spring-biased switch arm. The disc moves to an inverted dished configuration with snap action to move the switch arm to a trip position against the arm bias when the diaphragm moves in response to application of a selected fluid pressure. The disc remains in its inverted shape to releasably hold the arm in tripped position until the switch is manually reset even when the diaphragm returns to its original position after removal of the selected fluid pressure from the diaphragm. A push button or push button means is selectively movable to apply a force to the disc sufficient to restore the disc to its original disc configuration after the fluid pressure is removed from the diaphragm, thereby to permit the switch arm to reset in response to its spring bias and provide trip-free manual reset switch operation.

Pressure responsive switch

The disclosure relates to a method and apparatus for on-line calibration of disc thermostats. A disc thermostat is initially provided in assembled condition, the gap at the switch measured and compared with a predetermined optimum gap, the error magnitude determined and a device operated to alter the position of the disc and transfer element relative to the switch to provide the predetermined optimum gap. A feedback generator station tests a prior thermostat during disc snapping for disc velocity and switch opening and provides a fine tuning adjustment signal to alter the predetermined optimum gap on-line.

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Versailles, KY, United States of America

Werner Strasser