Abstract: An ultrasonic wave transmitter and receiver adapted to be mounted on the rear portion of a vehicle to detect the distance between the rear end of the vehicle and any obstruction located at the rear side of the vehicle. The ultrasonic wave transmitter and receiver includes an ultrasonic transducer attached to a lower part of the vehicle at a portion spaced from the rear end of the vehicle in the forward direction of the vehicle by a predetermined distance, a horn opening rearwardly from the vehicle and a wave guide tube through which the horn and the ultrasonic transducer are coupled to each other. The distance between the ultrasonic transducer and the rear end of the vehicle is selected to correspond to a time length which is long enough to sufficiently attenuate the residual oscillation of the ultrasonic transducer.

Abstract: An ultrasonic transducer which is suited to be placed in the place exposed to water, comprises an ultrasonic vibrator which transmits and receives ultrasonic wave, a horn which imparts directivity to the ultrasonic wave and a bent wave guide which connects the ultrasonic vibrator and the horn, and a reflecting plate which is provided in the bent portion of the wave guide for guiding the ultrasonic wave into the horn or the ultrasonic vibrator. According to the ultrasonic transducer of the present invention, the ultrasonic vibrator can be positioned above the horn when the horn is horizontally disposed. Therefore, the ultrasonic vibrator is not splashed with water entering from the horn.

Abstract: A rear obstacle detecting system for automotive vehicles includes an ultrasonic transmitter/receiver unit, distance detecting unit and an indicator for measuring distance to an obstacle while a vehicle is in backward movement. The ultrasonic transmitter/receiver unit having a ultrasonic vibrator is always energized as long as the vehicle is in an operating condition irrespective of whether the vehicle is in a backward movement or not, in order to maintain the ultrasonic vibrator being vibrated to achieve a self-cleaning function. The indicator is energized only when the vehicle is in backward movement.

Abstract: A hollow tubular handle is connected at one end to a pressurized water supply and carries a sprinkler head at its other end. A brush attached to the sprinkler head is formed with a hole through which water from sprinkler head passes without contact with the brush. A tubular member extends from the sprinkler head partially through the hole in the brush to prevent the bristles of the brush from being bent into the flow from the sprinkler head when the brush is pressed against a surface to be washed such as an automobile body.