Turbocharger having a device for detecting a malfunction of the turbocharger and a method for detecting such a malfunction

A turbocharger having a device for detecting a malfunction of the turbocharger, in particular a malfunction of at least one bearing of the turbocharger, wherein

• a) the device for detecting a malfunction of the turbocharger comprises a memory device, in which the desired rotational speed curves of an intact turbocharger are stored as a function of a mass flow of the exhaust gas for different engine oil temperatures and/or exhaust gas temperatures,
• b) the device for detecting a malfunction of the turbocharger further comprises a comparing device, in which a detected actual rotational speed curve is compared to the corresponding desired rotational speed curve of an intact turbocharger, with the comparing device selecting the desired rotational speed curve of the intact turbocharger as a function of a determined engine oil temperature and/or the exhaust gas temperature or an engine oil temperature or exhaust gas temperature which can be compared to the determined engine oil temperature or the exhaust gas temperature,
• c) the turbocharger further comprising a measuring device for determining an actual rotational speed curve of the turbocharger as a function of a mass flow of the exhaust gas and for determining the engine oil temperature and/or the exhaust gas temperature of the turbocharger, and wherein
• d) the device for detecting a malfunction of the turbocharger issuing an error message if the comparing device detects that the actual rotational speed as a function of the mass flow of the exhaust gas lies outside a tolerance range of the desired rotational speed of an intact turbocharger.

A method for detecting a malfunction of a turbocharger, in particular a malfunction of at least one bearing of the turbocharger, comprising the steps:

• a) Determining a desired rotational speed curve of an intact turbocharger,
• b) Measuring the actual rotational speed curve of the turbocharger,
• c) Comparing the actual rotational speed curve of the turbocharger to a corresponding desired rotational speed curve of the intact turbocharger,
• d) Detecting a malfunction of the turbocharger if die actual rotational speed reaches a limit rotational speed within a period of time and the period of time in this process lies outside a tolerance range for a desired period of time, within which an intact turbocharger with intact bearings reaches the limit rotational speed.

A method for detecting a malfunction of a turbocharger, in particular a malfunction of at least one bearing of the turbocharger, comprising the steps:

• a) Determining desired rotational speed curves as a function of a mass flow of the exhaust gas of an intact turbocharger for different engine oil temperatures and/or exhaust gas temperatures,
• b) Determining the actual rotational speed curve of the turbocharger as a function of a mass flow of the exhaust gas and determining the engine oil temperature and/or the exhaust gas temperature,
• c) Comparing the detected actual rotational speed curve to the corresponding desired rotational speed curve of the intact turbocharger, with the desired rotational speed curve of the intact turbocharger is selected as a function of the determined engine oil temperature and/or the exhaust gas temperature or of an engine oil temperature or exhaust gas temperature which can be compared to the determined engine oil temperature or the exhaust gas temperature,
• d) Detecting a malfunction of the turbocharger if the actual rotational speed as a function of the mass flow of the exhaust gas lies outside a tolerance range of the desired rotational speed of an intact turbocharger.