NVH measurements on HVAC compressor systems

Application note for IPEmotion & Mx-SENS2 4

Automotive manufacturing companies dedicate a lot of attention to the development of sophisticated airconditioning
systems in order to increase the passenger and driver comfort. During operation – when cooling capacity is generated – undesired noise can occur, caused by the refrigerant compressor, mechanical vibrations of the pipework or the ventilation system.

The challenge

To ensure the repeatability of NVH tests, various thermodynamic parameters of the HVAC system must be monitored very closely. Usually the following parameters are measured: refrigerant pressure, intake and outlet gas pulsation, temperatures, compressor speed (RPM), airborne noise, vibration- and force measurements on the mounting brackets. In addition to the analog inputs several parameters of the engine and climate ECU can be recorded simultaneously. The combination of analog inputs and ECU data expands the analytic database significantly. It is helpful to identify the cause of certain noise characteristics.

Requirements

  • Dynamic vibration measurements with IEPE sensors
  • Acoustic measurements with 100 kHz sample rate
  • Synchronous CAN bus measurement on vehicle ECUs
  • Temperature and other analog measurement inputs

The solution

NVH tests of HVAC systems can be carried out systematically with the help of the data acquisition software IPEmotion and the device Mx-SENS2 4. The modular platform provides high-channel data acquisition system with IEPE sensors for NVH signals (up to 100 kHz sampling rate per channel), and other sources of analog and digital inputs as well as CAN bus data from ECUs. The software supports calibration functions to change parameter setting of the ECU and to control e.g. compressor RPM through LIN bus commands as well. This extensive database offers various options for analysis and export. For example a data check to pinpoint background noise or signal overload, a direct audio playback of recorded raw data and FFT analysis of NVH channels can be made by using various diagrams – including the Campbell diagram. Together with the possibility to export data in the ATFX format into software from other companies, IPEmotion and Mx-SENS2 4 provide you with a completely carefree package.

The advantages

IPEmotion offers dynamic data measurements by combining multiple sources like CAN data from the vehicle ECU and a large range of analog and digital modules (including dynamic high channel count inputs with sampling rates up to 100 kHz).

  • Modular hardware design that provides a high level of flexibility and scalability regarding the number of
    measurement inputs
  • Small and ruggedized analog devices supporting an extended temperature range of -40 to 105 °C. This provides a high flexibility for decentralized installations in the engine compartment close to the sensors.

Download the whitepaper of this real-life example