Trw Limited

Stephen R Cooper

Neil Gordon Murray, Jr

Frederic Marcel Sejalon

Michelle Renee Schaffran

An ultrasonic transducer (10) includes a housing (12) having a main section (14) and a base section (16). Retainer elements (20) on the main and base sections (14 and 16) of the housing (12) are engageable only when the main and base sections of the housing are in a predetermined orientation relative to each other. The retainer elements (20) press the main and base sections (14 and 16) of the housing (12) together and securely interconnect the main and base sections of the housing. A diaphragm (82) is formed in an end portion of the main section (14) of the housing (12) opposite from the retainer elements (20). A ridge (88) projects axially outward from the diaphragm (82) to protect the diaphragm and decouple the diaphragm from a side wall (74) of the housing (12). Acoustically absorptive material (114 and 116) is disposed in the housing.

Ultrasonic transducer

An ultrasonic sensor system (40) has a transducer (44) that emits an ultrasonic signal (52), in response to an electrical excitation signal (50) from driver/receiver circuitry (46), and outputs an electrical response signal (56), in response to receipt of a reflected ultrasonic signal (54) from an occupant (54). The transducer (44) rings-down upon termination of the excitation signal (50). The transducer (44) has a natural resonant frequency that is subject to change. In an occupant sense mode, a receiver portion (68) of the driver/receiver circuitry (46) and a controller (30) process the response signal (56), resulting from transducer excitation at a predetermined frequency, to determining distance between the transducer (44) and the occupant (14). In an adjust mode, the controller (30) varies the frequency of the excitation signal (50) over a range of frequencies, and monitors the ringdown of the transducer (44) during the variation of the frequency to determine a current natural resonant frequency of the transducer (44). The controller (30) changes the predetermined frequency to the determined natural resonant frequency, so that subsequent operation in the sense mode utilizes the resonant frequency.

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Fowlerville, MI, United States of America

Stephen R Cooper