Abstract: A temperature sensing transducer has a mechanically vibrating member whose rigidity varies with temperature, changing the resonant frequency. An output signal is generated having a frequency controlled by the vibrating member. The rigidity is caused to vary with temperature by making the vibrating member from a material whose modulus of elasticity is sensitive to temperature changes in the desired measurement range. Also by making the vibrating member of a bimetal shaped as a frusto-conical disk, the rigidity of the disk changes with temperature due to internal strains.

Abstract: A gas damped acceleration switch for use as a vehicle crash-sensing device. A mass is supported for movement along an axis against a spring, the mass actuating a switch only after moving a predetermined distance against the spring by an accelerating force. A gas damping system makes the device sensitive to the duration as well as the magnitude of the velocity change. Damping is provided by a plate movable with the mass having surfaces that are perpendicular to the axis of motion. The plate is normally pressed against a mating surface to exclude air. A seal is formed between the mating surfaces around the periphery so that a partial vacuum is formed as the mass moves the surfaces apart. When the surfaces move apart a predetermined distance, the seal is broken and the pressure equalizes. However, the moving plate still produces viscous damping as a function of velocity as it continues to be moved through the air by acceleration of the mass against the spring.

Abstract: An electric heater for heating diesel fuel includes a housing having an inlet and an outlet. A flat disk-shaped PTC thermistor is centrally mounted in the housing and is arranged so that the inlet directs fuel against one side of the thermistor to divert the flow of fuel outwardly around the marginal edges of the thermistor. An electrical resistance heater unit surrounds the thermistor between the walls of the housing and the thermistor and is provided with spaces through which the outwardly diverted fuel passes. A divider wall in the housing spaced from the heater unit and thermistor directs the fuel passing through the heater unit across the opposite side of the thermistor to the housing outlet. The PTC thermistor and electric heater unit are connected electrically in series whereby the thermistor functions to control heating output of the fuel heater in accordance with ambient temperature conditions.

Abstract: A glow plug control circuit uses two normally closed thermally actuated switches in series with a power relay and a timer switch across the battery when the ignition switch is turned on; the power relay connects the glow plugs to the battery. At least one of the two switches cycles on and off to limit the temperature of the glow plugs. Another normally closed thermally operated switch has a heating element in series with the glow plugs for turning off a lamp after the glow plugs are energized for a predetermined time. If one or more of the glow plugs are open-circuited, the lamp is cycled on and off with the cycling on and off of current through the glow plugs by the power relay, to signal a fault condition.

Abstract: A diesel fuel filter in which wax crystals that tend to clog the filter at low ambient temperatures are directly heated to melt the crystals, allowing them to pass through the filter. A low energy heating element is positioned adjacent the filter element in the region where wax normally accumulates. The heater melts the wax without significantly raising the temperature of the fuel.

Abstract: A crash-sensing switch assembly for breaking an electrical circuit has a weight pivotally supported on a horizontal surface with the center of gravity above the surface. The weight is free to move away from the surface if the assembly is inverted. Movement of the weight away from the surface, either by tilting or falling, brings the weight into engagement with the trip lever of a latch, releasing a switch to break the circuit.

Abstract: A snap-action thermal relay in which a thin sheet of spring material having a central opening is mounted at one point along one edge and is crimped along an adjacent edge to distort the sheet into a slightly convex bowed shape. A heater element in the form of a thin band of metal is anchored at either end to the normally convex surface of the sheet adjacent opposite edges of the sheet, with a bridging member inserted between the band and the sheet to put the band under tension. A printed circuit heating element is applied to the band on the side opposite from the sheet. The tension in the band holds the sheet in a concave bowed condition. Heating of the bank reduces the tension in the band and allows the sheet to snap back to its normal convex bowed condition. This action brings the band into direct thermal contact with the convex surface of the sheet over a substantial length of the band to provide good conductive transfer of heat from the band and heater to the spring sheet.

Abstract: The sensor includes a linearly movable mass including two sections and spring means urging one of the sections into operative engagement with means including an actuating element. The sensor also includes means releasably securing the two sections together and means releasing the securing means when the two sections have moved a predetermined distance against the urging of the spring. The two sections may be rollers of a rolamite unit. A flexible band extends around a portion of the two rollers. One example of a use for such a sensor is in an air bag safety restraint system.

Abstract: A mechanical sensor, operable without any source of electrical energy, includes: a rolamite means, a support means for the rolamite means, a trigger means, a hammer means, a primer means and a biasing means. The rolamite means is responsive to acceleration or deceleration above a predetermined amount and is mounted on the support means. The support means provides a path of movement for a portion of the rolamite means during deceleration. The trigger means is located adjacent to the support means and has a first portion and a second portion. The first portion of the trigger means extends into the path of movement for a portion of the rolamite means. The hammer means is located adjacent to the trigger means and is releasable by the trigger means. The primer means is activated by the hammer. The biasing means biases the hammer means toward the primer means.

Abstract: A sensor which utilizes the difference in thermal characteristic between two fluids to detect the presence of one fluid or the other. A continuously heated thermal expansion element activates a switch. When the element is brought in thermally conductive contact with a liquid, the heated element drops in temperature, shortening the length of the expansion element and activating the switch.

Abstract: A solenoid in which the coil is positioned inside a housing of magnetic material. The housing has a tubular projection forming a recess in the inside of the end wall along the axis of the coil, one end of the plunger projecting beyond the coil into the recess when the plunger is in the energized position. The portion of the plunger that extends into the recess is tapered to obtain a constant force-displacement characteristic for the full travel of the plunger.