Ultrasonic distance sensor and a method for protecting an ultrasonic transducer in an ultrasonic distance sensor

A method for protecting an ultrasonic transducer of a distance measuring sensor, the distance measuring sensor comprising:

• a main housing, and
• an ultrasonic transducer located in the main housing, the ultrasonic transducer having an output face through which an ultrasonic signal is transmitted,
• the main housing having a communicating aperture therein for accommodating a transmitted signal from the ultrasonic transducer therethrough,
• the method comprising:
• providing a protective element protecting the ultrasonic transducer from a corrosive or hazardous environment into which the signal from the ultrasonic transducer is to be transmitted,
• providing the protective element with a central working portion having a first major surface and a second major surface opposite the first major surface,
• providing an outer peripheral portion extending around the central working portion, the outer peripheral portion having a first major surface and a second major surface opposite the first major surface thereof,
• locating the protective element in the housing with the outer peripheral portion engaging the housing and extending around the communicating aperture with the protective element sealably closing the communicating aperture, and with the first major surface of the central working portion abutting the output face of the ultrasonic transducer, wherein the method further provides:
• providing the central working portion of a deformable resilient material with the first major surface of the central working portion being convex in a relaxed state thereof,
• urging the output face of the ultrasonic transducer into engagement with the first major surface of the central portion to deform the central portion to reduce the concavity of the first major surface thereof to a substantially planar first surface so that the first major surface of the central working portion is urged into tight resilient abutting engagement with the output face of the transducer,
• providing the central working portion between the first and second major surfaces thereof to be of thickness less than the thickness of the outer peripheral portion between the first and second major surfaces thereof, and
• providing the central working portion to transition into the outer peripheral portion through a flexion zone extending around the central working portion between the central working portion and the outer peripheral portion to permit flexing of the central working portion relative to the outer peripheral portion thereof during transmission of the signal from the ultrasonic transducer so that the central working portion vibrates with the output face of the ultrasonic transducer to minimize the attenuating effect on the transmitted ultrasonic signal from the ultrasonic transducer.