Method for producing an ultrasonic transducer core with embedded piezoelectric transducer elements

Abstract

The invention relates to a method for producing an ultrasonic converter core (2) comprising at least one piezoelectric converter element (4) and at least one adaptive body (8), for promoting a vibration coupling between the piezoelectric converter element (4) and a surrounding medium, and at least one temperature expansion compensating member (6) with the following steps: - insertion of the piezoelectric converter element (4) in a moulding tool; - insertion of the adaptive body in the moulding tool; - insertion of a moulding mass in the moulding tool such that the moulding mass forms a force-fit connection, a chemical bond and / or a form-fit connection with the adaptive body (8) and the piezoelectric converter element (4); and - hardening of the moulding mass for the formation of the temperature expansion compensating member (6). The invention further relates to an ultrasonic converter core (2) particularly manufactured according to the method.

Description

technical field [0001] The invention relates to a method for producing an ultrasonic transducer core and to an ultrasonic transducer core. Background technique [0002] The invention relates to an ultrasonic transducer, which is used as a flow meter, for example in the field of method technology or in the automotive field (in particular for the measurement of volume flow or mass flow in the air intake and / or exhaust of internal combustion engines); or Use as environmental sensors, in particular in the front and / or rear of the bumper of the vehicle, for example for parking assistance systems and / or collision avoidance systems. Typical ultrasonic transducers are used here: they not only transmit ultrasonic waves into a fluid medium (for example air, gas and / or liquid), but also receive ultrasonic waves. Ultrasonic signals are usually transmitted via a fluid medium from the transmitter to the receiver or from the transmitter into the environment and the reflected ultrasound si...

AI Technical Summary

Problems solved by technology

[0003] A disadvantage of many known ultrasonic flowmeters is that, at least in the case of media in gaseous form, in the case of a small signal path, that is to say a small change in the running time, the change in the running time makes the method slow down. It is often very easy to drift when the rate is small

It is therefore difficult to achieve or even improve the usual tolerances in thermodynamic flow measurements

[0009] That is to say, a disadvantage of the known systems is that these systems are usually strongly subject to design constraints

The disadvantage of embedding the piezoelectric transducer element directly in the adaptation layer is that the piezoelectric transducer element differs from the adaptation body with regard to the coefficient of thermal expansion, which affects the ultrasonic waves, especially during cooling and / or multiple temperature cycles. Converter Cores Bring Problems

Such cracks can lead to complete damage on the ultrasonic sensor, since there is hardly any signal available for measurement due to the large acoustic impedance to be overcome

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