Abstract: The present invention relates to a method and a device for monitoring an exhaust-gas turbocharger of an internal combustion engine. In order to create an inexpensive and also reliably operating method and a corresponding device for monitoring an exhaust-gas turbocharger, it is proposed that a sound transducer which is designed to record rotational-speed dependent turbocharger operating noise is provided, which sound transducer is connected to an electronic system for frequency analysis for the output of a turbocharger rotational speed signal.

Abstract: A sensor circuit for a flow sensor comprises terminating impedances connected in parallel to the sound transducers and has a signal generator, which is configured as a power source. The circuit arrangement is suitable particularly for the operation of an airflow sensor in internal combustion engines.

Abstract: A device is provided for determining a mass flow of a first gas flowing in a flowing channel of an internal combustion engine of a motor vehicle. The device includes: sound transducers arranged at respective ends of a measuring path for providing sound signals, a temperature sensor for determining a temperature of an overall mass flowing in the flow channel, and an evaluation unit arranged downstream of the sound transducers. The evaluation unit is capable of carrying out the following: determining a flow rate of the overall mass and a speed of sound based on delay times of the sound signals, determining an overall mass flow based on the flow rate, the temperature, and a pressure of the overall mass in the flowing channel, ascertaining a proportion of a second gas flowing in the flow channel at a temperature above 10° C. and based on the speed of sound and the temperature, and correcting the overall mass flow to obtain the mass flow of the first gas.

Abstract: The present invention relates to a method and a device for monitoring an exhaust-gas turbocharger of an internal combustion engine. In order to create an inexpensive and also reliably operating method and a corresponding device for monitoring an exhaust-gas turbocharger, it is proposed that a sound transducer which is designed to record rotational-speed dependent turbocharger operating noise is provided, which sound transducer is connected to an electronic system for frequency analysis for the output of a turbocharger rotational speed signal.

Abstract: A sensor circuit for a flow sensor comprises terminating impedances connected in parallel to the sound transducers and has a signal generator, which is configured as a power source. The circuit arrangement is suitable particularly for the operation of an airflow sensor in internal combustion engines.

Abstract: A device is provided for determining a mass flow of a first gas flowing in a flowing channel of an internal combustion engine of a motor vehicle. The device includes: sound transducers arranged at respective ends of a measuring path for providing sound signals, a temperature sensor for determining a temperature of an overall mass flowing in the flow channel, and an evaluation unit arranged downstream of the sound transducers. The evaluation unit is capable of carrying out the following: determining a flow rate of the overall mass and a speed of sound based on delay times of the sound signals, determining an overall mass flow based on the flow rate, the temperature, and a pressure of the overall mass in the flowing channel, ascertaining a proportion of a second gas flowing in the flow channel at a temperature above 10° C. and based on the speed of sound and the temperature, and correcting the overall mass flow to obtain the mass flow of the first gas.

Abstract: The invention relates to a product (1,9) of metal formed with a hole (5,8,17), particularly a rock drill steel, and provided with an element (10,12,14,15,16,18) for damping sound producing waves in the product annoying for the human ear. The sound damping element is arranged in the hole in the product and has a cross section less than the cross section of the hole. The damping element has at least one contact surface loosely arranged relative to the wall of the hole and located between the nodes of the waves so as to create at least one wave damping effect.